3 r '/ 
 1357^ 
 
 iliiiiiiiiiiiilif^ 
 
 MAX l\ MEYER 
 
arV13570 
 
 A brief ""aJlVIS'i 
 
 Cornell University Library 
 
 77^24 031 223 898 
 
 olin,anx 
 
Cornell University 
 Library 
 
 The original of tliis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924031223898 
 
A BRIEF MANUAL 
 
 PSYCHOLOGY 
 DEMONSTRATIONS 
 
 TO ACCOMPANY AS ILLUSTRATIVE MATERLA.L 
 AN ELEMENTARY COURSE 
 
 THE PSYCHOLOGY OF THE OTHER-ONE 
 
 BV 
 MAX F. MEYER 
 
 Professor of Experimental Psychology 
 in I he Uiiiversily of Missouri 
 
 (Salumbia, jfflisaauri 
 
 THE MISSOURI BOOK COMPANY 
 PUBLISHERS - 
 
 1922 
 11 
 
COPYRIOHT 1922 
 
 The JIisso'uri Boqk Co. 
 
PREFACE 
 
 This book has not been entitled either "psychological 
 experiments" or "psyeliological laboratory exercises" be- 
 cause it does, not offer either that which is impossible 
 or that which but few college students need. 
 
 It is impossible to teach anybody how to open up — by 
 experiment, like a Galileo — into an unexplored region 
 of the world new avenues of understanding. One can 
 "teach" only that which is "already known." Experi- 
 ments can not be taught; Thej^ must be invented. 
 
 To teach — thru exercises — how to take measurements 
 by the skilful use of existing apparatus, is indeed pos- 
 sible. But the demand for that instruction in measure- 
 ment is relatively small among beginners, in psychology 
 as in any science. And for advanced students who spe- 
 cialize in psychology there is no dearth of good labora- 
 tory manuals. 
 
 This book is not intended to be used alone, but only as 
 an auxiliary — and a rather essential auxiliary — to the 
 author's text-book. Psychology of the Other-One. 
 
 No text-book in any science can rely totally on the 
 student's ability to illustrate the theories taught — and a 
 text-book ought to teach scientific theories! — by using 
 as illustrative material only his previous life experience. 
 Therefore graphic illustrations are used in texts and 
 demonstrations in class rooms. 
 
 It is well known, for example, in anatomy, that the de- 
 monstrative value of a dissection is greater when the 
 
 (1) 
 
Z PREFACE 
 
 student applies his own hands than when he is a mere 
 onlooker at a dissection made by the demonstrator. 
 
 This book will help that student who uses the author's 
 introductory text, to apply his own hands to the demon- 
 stration of certain not quite ordinary experiences with 
 other people (not with his consciousness). No demon- 
 stration has been included merely because of its value 
 as a curiosity. No illusion is included merely because 
 it is an illusion. All these demonstrations illustrate 
 and therebj' further clarify the theories of which the 
 text is composed. Any demonstration which has no such 
 definite relation, has been rigorously excluded no matter 
 how much the omission may hurt the book in the eyes of 
 him who looks for "what is customarily included." 
 
 Like the Psychology of the Other-One this book is 
 written for the use of college freshmen and shows inci- 
 dentally with what aims the elementary (beginners') 
 course in psychology has been taught in the University 
 of IMissouri for more than two decades. 
 
 ilAx F. ]\Ieyer 
 The University of ilissouri 
 
Introductory Advice. 
 
 The student should, at the begimiing of the course hi 
 the Psj'chology of the Other-One, (.-hoose a partner on 
 whom to make the demonstrations enumerated below. 
 It is true that he can make some of these demonstrations 
 on his own body, asking himself the questions and an- 
 swering them himself. For example, working with the 
 eolor-wheel, he can ask himself wliether the disk deserves 
 to be called colorless. But he can not easily measure , 
 his own reaction time or run a maze and at the same time 
 keep the records required. 
 
 All the demonstrations given here can, and preferably 
 should, be made on the Other-One. This is not a course 
 in introspective psychology. The famous warning 
 ' ' Know Thyself ' ' really means : Know the ' other fel- 
 lows, including in this knowledge the opinion which they 
 hold of you. 
 
 In making the demonstration, follow the advice given 
 in this manual ; but also compare the text-book ; and 
 whenever you have exhausted your resources, do not 
 hesitate to ask the instructor's advice. He is not j^our 
 enemy. 
 
 In. writing up your demonstrations, use common sense. 
 Avoid unnecessary words. But write — make this your 
 standard to judge by — enough to feel satisfied that if 
 you should read your notes again after a year 's interval, 
 the wliole demonstration would again be clear to you. 
 Remember, — be brief. That epoch is past when teachers 
 
 (3) 
 
4 J'SYCJIOLOGY DEJIONbTlfATIONS 
 
 based tlie marks they gave to students on the weight of 
 the paper filled by them during an examination period. 
 You will be i^raded on the basis of tests proving what 
 you have aceomplished, not on how much you have writ- 
 ten in your note book or on a test paper. Do not copy 
 in your note book sentences from this manual or from 
 your text. 
 
 Do not misunderstand what has just been said as 
 meaning that you should abstain from writing when 
 you study. On the contrary, no better advice can be 
 .li'iven to you than to answer the questions which you find 
 printed in the Ijack of the text-book, not only orally, but 
 in ^\'riting. 
 
 I. The Time of a Beaclion, Simple or Choice. 
 
 The reaction time is reeofiiiized to be one of the most 
 fundamental facts with \vhieh the psychology student 
 must be familiar. In order to familiarize yourself with 
 it, you will measure your partner's reaction time in the 
 case of a simple I'caction and also in the case of a choice 
 reaction. 
 
 When reading of "choice," dp not think of anything 
 subjective like a power of the soul or a mysterious en- 
 tity like the one represented by the "deus ex machina" 
 on the Greek stage. Choice means that the stimulation, 
 and with it the response, "varies from time to time," as 
 you will vary it here. 
 
 There are very many time measuring instruments 
 which have been invented for the measurement of du- 
 rations of time from a few seconds down to a thousandth 
 part of a second. That instrument which you will use 
 hei'e was in^-entcd l>y Professor Sigmund Exner of the 
 
REACTION TIME 5 
 
 University of Vienna and called hy him "neuramebi- 
 meter," that is, "nervous flux recorder." See sketch 
 on page 46 of your text. 
 
 This instrument measures the reaction time in hun- 
 dredths of a second. It is very simple, fairly fool-proof, 
 and gives you a chance to learn incidentally about the 
 method of registering a momentary event by a mark 
 made on a smoke covered and moving surface. 
 
 Tal5:e out the glass slide and smoke it on its proper 
 surface over a candle. After taking one record, you re- 
 move the glass again and reinsert it with ends exchanged, 
 so that one smoking will permit you to record two re- 
 action times. After that you wipe the glass clean with 
 a towel. In order to smoke the glass, take one end be- 
 tween your fingers, touching with your fingers the 
 groimd edges and thus leaving the surface to be smoked 
 virtually free. Steadily move the glass in a quick motion 
 lengthwise back and forth thru the flame. Remember 
 ' ' move. ' ' Do not hold it still. You do not want to heat 
 the glass and burn your fingers. Be patient and soon 
 you will see the surface covering itself with a uniform 
 gray layer of fine soot. Then take hold of the other end 
 and smoke the place which (in order to save your fing- 
 ers) you have not yet moved thru the flame. 
 
 Remember "thru the flame," not above the flame. 
 But do not touch the wick, or you will get candle grease 
 on the glass. Remember "gray." You do not want 
 the glass black, for you do not want to provide more 
 work for the laundry than is unavoidable. 
 
 When the smoked glass slide is in place, with the vi- 
 brating spring bent sidewise and resting against the big 
 pin, see to it that the writing point has neither too much 
 nor too little friction on the glass. 
 
6 PSYCHOLOGY DEMONSTR.\TIONS 
 
 Xow seat your partner comfortably ^ou a chair (s't 
 down yourself, too) and tell him to touch (not to weight) 
 the button with the index finger of his better hand. Make 
 him close his eyes and instruct him to press down the 
 button with the greatest possible speed as soon as he 
 hears the rather low and dull tone of the vibrating reed, 
 the big steel spring. Give him first a little practice in 
 doing this, before inserting the smoked glass, and thus 
 without taking any record. 
 
 When you pull the hook, be sure that you hold it firm- 
 ly between the index finger and the thumb. Practice it, 
 pulling the whole slide entirely from its l>earings. It 
 must then be securely held by you in the air and not 
 drop on the floor. 
 
 Next to the glass tlie most breakable part of the in- 
 strument is the tin,y spring point which writes on the 
 smoked surface. Never move the slide backwards with- 
 out being sure that this point is safe (button down) 
 while you push tlie slide back. 
 
 You do not want ever to surprise your partner. We 
 do not in psychology .demonstrations play I ricks on each 
 other any more than we use magic. Therefore, two or 
 three seconds before pulling the hook (varying this time 
 a little) you say "Keady," so that he may get i-eady 
 and avoid surprise. 
 
 If you do not know how long tw-o or three seconds last, 
 look at the pendulum of the laboratory clock. It swings 
 from one side to the other in about two-thirds of a sec- 
 ond. Three swiiijis make two seco)ids, six swintis four 
 seconds, and so forth. 
 
 Test your partner and count the number of waves in 
 the smoke. Each wave, from valley to valley, lasts one 
 
REACTION TIME ( 
 
 hundredth of a second. If the last visible wave is iiicom- 
 plete, count it one provided you see more than one-half 
 of it. If less, do not count it. 
 
 If you count less than ten waves, disregard that tcsr. 
 Either one of two possible mistakes has occurred. Your 
 partner, instead of reacting to the tone signal, may 
 simply have become impatient Math watchful waiting 
 after hearing you say "Ready." Or your partner did 
 not follow your order barely to touch the button, but 
 weighed his hand on it, letting it rely on the friction 
 between the big spring and the pin. As soon as you be- 
 gin to pull, that friction changes from rest friction to 
 motion friction. The latter, as you learn in physics, is 
 very much less powerful. Therefore now by mere gravi- 
 ty your partner's hand and arm (even if — imagine — 
 they had been cut off at the shoulder) would push the 
 button down. But you do not want to measure the re- 
 action time of gravity working against friction. A nor- 
 mal human reaction time can not be reduced to less than 
 ten hundredths of a second. 
 
 Take fifteen tests. Write dowji in your note book 
 the fifteen numbers counted as well as their average. 
 Learn at this time that j'ou will never find men of 
 science satisfied with being told an average alone, with- 
 out any indication of how those actual test values varied 
 from which that average was computed. Don't use 
 decimals in computing the average. Choose the' nearest 
 integer. 
 
 If you are interested in knowing how you could save 
 paper space by substituting for the many test values a 
 mere statement of the average deviation, ask the instruc- 
 tor how to compute that deviation. But this is not re- 
 quired. 
 
b I'SYCI-IOLOGY DEi\:ONSTRATIONS 
 
 Xow ask your jiartner what average reaction time he 
 found when he tested you. Notice how people may dif- 
 fer. 
 
 After liavijig thus measured yonr partner's simple re- 
 action time, measure his time of a choice reaction. Pro- 
 ceed in exactlj' the same way as with the simple reaction 
 time, with the following additions and exceptions. 
 
 Put the index finger of his second best hand on the 
 button of a contact key which will cause tlie striking of 
 a gong when the button is pushed down. Then instruct 
 your partner to <;'et ready to react with either hand, but 
 to react with the second hand alone whenever you say 
 "Gong" and with the best hand alone whenever you say 
 "Noo" (for neuramebimeter). 
 
 Make for your own use, secretly, a list of fifteen times 
 the word "gong'' and fifteen times tlie word "noo, " 
 mixed at random. 
 
 Pronounce your word vui'y quickly and very distinctly 
 at the very moment when you pull the hook. You may 
 have to pull the slide now more sbnvlij than in taking 
 the simple reaction time, and you may have to pull it 
 clear out of its bearing in order to get all the waves 
 wi'itten on it. 
 
 When you he;ir the gong striking altho you did not 
 say "Gong," make a cross in your list indicating an 
 error. 
 
 If your partner should raise the writing point of the 
 neuramebimeter and thereby interrupt the wave line 
 altho you did not say "Noo," save the time of counting 
 the waves. Simply make an error cross in your list. 
 
 You are likely to get fewer tlian fifteen correct re- 
 tidion times. Put they will suffice for this demonstra- 
 tion. 
 
REACTION TIME 9 
 
 Ask your partner, for comparison, what average choice 
 reaction time he found when he tested you, and also 
 what number of errors he found with you. Notice 
 first, whether all people are equally fast; and second, 
 ^^•hether they are equally apt to fall into errors. 
 
 II. The Formation of a Multiple Eabit of the Serial 
 
 Type. 
 
 Warning: Do not go about in the laboratory looking 
 at the mazes used by other pairs of students. Seeing 
 them spoils your own work completely. 
 
 Our text (p. 124) has taught us that all types of habit 
 formation can be reduced to one simple and fundamental 
 type. Two stimuli must be applied with no great time 
 interval between them. (The longer that interval, the 
 weaker the habit: "10 seconds stimulation interval"- — 
 "very weak effect.") Remember: there are always tico 
 stimuli. 
 
 The two (complex) nervous currents are served by a 
 longer and common path. Each of the currents is also 
 served by a shorter path which each of the two functions 
 (either reflexes or old habits) possesses separately from 
 the other function. The habit formation consists in the 
 reduction of the resistance of that longer and common ■ 
 path. Compare the figure of page 124 of your text. 
 
 The change occurring in the nervous system, as de- 
 scribed in the text more fully, can be stated iti brief and 
 more abstract form as follows, in two stages (which, 
 however, are not successive in fact). 
 
 Warning: Do not confuse "susceptibility" with "con- 
 ductivity." Consult the index of your text. 
 
10 PSYCHOLOGY DEMONSTRATIONS 
 
 Ffrsi Stage. 
 
 Condition : The black lines suffer a double influence 
 because of the double stimulation. 
 
 "Limit" which this influence approaches (tho never 
 reaches) : The resistiince oF the black lines approaches 
 zero. 
 
 (Joiic/n.sioii : A current coming from S„ now divides 
 (with ever increasing ai)proximation) in hahes, that is, 
 equally, at Sa. 
 
 Assiimjdion made previously on broader grounds than 
 the present necessity: The "higher" neuron Si Sab 
 is more susceptible than the "lower" neuron S,i ^\l 
 
 Total Conclusion: Finally all the current would go 
 from S,{ upwards to the higher center. Nothing then 
 goes from S^ to the right. (Psychology of the Other- 
 One, page 127, line 4.) 
 
 Second St((fjc. 
 
 Coiidilion: The ilouble sliinulation is always applied 
 more strongly at S,, than at S,,. 
 
 ('(inclusion : The i'esist;inee from ^1,?,, to Mb is more 
 quickly reduced than the resistance from Ma^f, to Ma. 
 
 Final Covrlnsion : Most (or all) of the current from 
 separate stimulation ol' Sa now goes (I) from S,i up- 
 wards and (11) from M„|, down to the right, to ?tlb. 
 (Psychology of the Other-One, |>iigc 127, line 6.) 
 
 It is self-evident that the changes in the nervous sys- 
 tem here in question must be the greater, the stronger 
 and the longer the stimulation. .Many stimuli either 
 can not be strengthened or <'aiinot be prolonged without 
 ceasing to be what they are to'be. For example, a word 
 
MULTIPLE HABIT 11 
 
 sound can not be prolonged to last a minute, — tl;at would 
 no longer be that word but a howl. Length of the 
 stimulation then can be secured only by frequent repeti- 
 tion of the stimulus. But the student must remember 
 that the total duration of the stimulation is here the de- 
 termining factor. There is no such thing as a fundamen- 
 tal ' ' law of frequency ' ' in habit formation. That is only 
 a corollary of the condition of length. 
 
 Neither is there any such thing as a fundamental ' ' law 
 of effect" in habit formation, altho it has spooked for 
 years in many psychology texts. Quite apart from the 
 fact that an explanation by effect would be teleology, 
 since science explains by causes, — that "law of effect" 
 is only a corollary of the condition that there must be 
 two sensory -motor functions (reflexes or old habits). 
 One stimulus alone cannot create a variation of its 
 response. The second response, that contained in the 
 second sensory-motor function, really is what those texts 
 vaguely refer to when talking of ' ' the effect. ' ' 
 
 A simple habit like the one represented by the figure 
 on page 124 of the text is acquired hy human beings so 
 quickly that the process of forming the habit can not 
 easih' be demonstrated as being a particular "function 
 of time." With animals this demonstration is possible 
 even in a simple habit. But our fellow men interest us 
 more than animals. Experiments to discover what that 
 mathematical "function of time" Avas, were therefore 
 first made — by Ebbinghaus — on multiple, not on simple 
 habits. The experiments by Ebbinghaus on the for- 
 mation of multiple speech habits are now regarded as 
 classic. He learned to recite a series of ten or twenty 
 nonsense syllables and thereby determined ' ' the learning 
 curve. ' ' 
 
12 PSYCHOLOGY DEMONSTRATIONS 
 
 Remember, that the only reason why, in determining 
 the learning curve, one did not experiment with a single 
 simple speech habit, was the fact that' in a human being 
 such a habit is often acquired in "no time." 
 
 FIFTH FIFTH SIXTH SIXTH 
 
 SOUND SPEECH SIGHT SPEECH 
 
 Use the figure to make clear to yourself that learning 
 a series of nonsense syllables is nothing other than a 
 multiple habit. 
 
 The fifth word-sound is most readily responded to by 
 pronouncing the fifth word; but there is the sight of the 
 sixth word which is responded to by the pronunciation 
 of the sixth word. The sentence just finished describes 
 the process of habit formation. 
 
 As soon as the habit is strong enougli, the two middle 
 ones of the four external factors have dropped out com- 
 pletely. As long as they have not dropped out complete- 
 ly, the habit is still weak. 
 
 The habit in its full strength functions Avith only the 
 first and fourth external factors. That is, the fifth word- 
 sound is directly responded to by the pronunciation of 
 the sixth word. 
 
 (Look at the figure! — At tlie beginning of the series, 
 substitute "first" for "sixth" in the third and fourth 
 factoi-s. Substitute in the first and second factors "in- 
 vitation sound" for "fifth sound" and "restating the 
 invitation sound" for "fifth speech.") 
 
MULTIPLE HABIT 
 
 13 
 
 Experiments to (iiscovei- the time function foi' multi- 
 ple habits of actions other than speech actions have been 
 made in later years especially in America, most fre- 
 quently by letting an animal run a maze. You will 
 demonstrate here the formation of a multiple habit by 
 letting your partner run a maze. 
 
 OO -^ (^ p 
 
 M„ 
 
 S6 Mi 
 
 Look at the figure ! — You see there the first factor in- 
 dicated by a double circle. This double circle is used 
 as a symbol for a situation presenting, after various pre- 
 vious maze turns and splits, more than one possibility of 
 proceeding in locomotion. You can now proceed by 
 taking either the continuation to the right or that to 
 your left. If tliere is anything in the situation which de- 
 termines your taking the good- tunnel, there is nothing 
 further to say. 
 
 If you take the bad tunnel, you run into a blind alley 
 which turns you back to its own entrance. The symbol 
 indicating the second factor in the figure represents 
 your action of entering and leaving behind that blind 
 alley. 
 
 The third factor is indicated by a composite of the 
 symbols of the first two factors. That is, the stimulation, 
 consists of the splitting tunnel plus "the stimulation 
 
14 PSYCHOLOGY DEMONSTRATIONS 
 
 resulting from" (populai-lj- speaking, "the experience 
 of") going into and out of the blind alley. 
 
 The fourth factor is indicated in the figure by a curve 
 bending in the other direction, leading to a double arrow 
 head, which reminds us of the possibility of unblocked 
 progress. 
 
 The last four paragraphs together describe the process 
 of habit formation. The habit in its full strength func- 
 tions with only the first and fourth external factors. 
 That is, the situation — of meeting, after various previous 
 maze turns and splits, this split of the tunnel — is now 
 directly responded to by taking the turn into the good 
 tunnel. 
 
 After having made aU this clear to your partner, you 
 ask the instructor to give you one maze and your part- 
 ner a different maze. No pictures of these mazes are. 
 shown in this manual because — you remember — seeing 
 the mazes in advance spoils your demonstration. One 
 of these mazes is a famous plaything of royalty, the so- 
 called Hampton court maze, but with some modifications. 
 All tlie shunts have beeji converted into blind alleys. 
 You then have nine different habits to form in order to 
 run the maze without being lured into any blind alleys. 
 The other maze is of a design th.at has been used fre- 
 ([uently for experiments with animals. You have to 
 form sixteen different habits in order to avoid all the 
 blind alleys. 
 
 You now place your maze well covered with a cloth 
 before your partner. Your partner places his maze 
 well covered before you. 
 
 If you want to look at yf)ur maze, do not uncover it 
 without being sure that your partner will not see it. 
 You have to uncover it in order to write down in your 
 
MULTIPLE HABIT 
 
 15 
 
 note book first a column of numbers from 1 to 16 (or to 
 9) and then to the right of each number in a second 
 column the letter R or L, according as the good turn is 
 either right or left. In a further column (you must 
 provide for several more) you will later make a cross 
 whenever you see your partner make a had turn. 
 
 Now get your watch ready, make your partner close 
 his ej-es, uncover your maze, put his finger in the center, 
 and when you like the position of the hands of your 
 watch, say "Start." 
 
 At the instant your partner drops out of the maze, 
 note down the time. Then cover your maze and only 
 then permit him to open his eyes. 
 
 Now convert minutes and seconds all into seconds and 
 write that number above the proper column. Below the 
 
 e^lOO 
 
 Qtrrors 7 
 
 column write the number of crosses, that is, bad turns, 
 errors. You need these entries, because at home you will 
 make a graph of the running of your maze by your part- 
 ner, like the sample shown. 
 
 You now take a rest by letting your partner make you 
 run his maze once. 
 
16 PSYCHOLOGY DEMONSTRATIONS 
 
 Then you make him run your maze once again ; and so 
 on alternately until you have seen your partner run your 
 maze without an error three times in succession. 
 
 Answer this question : "Why does the preceding para- 
 graph insist upon three times in sitccessionl Why is 
 "once without an error" not enough to stop? Discuss 
 then, the demonstration being finished for both, with 
 your partner tlie questions whether he is more clever 
 than you or the reverse, and whether one of the mazes 
 is more difficult to run than the other. (Both mazes are 
 now open to your inspection.) 
 
 You must after tliat — you should not do it before — 
 ask the instructor A\hether with animals one kind of 
 maze has been found to be easier than the other. 
 
 If your previous conclusion seems to be discrepant 
 with his answer, read chapter XVII of your text in order 
 to straighten the matter out. 
 
 Finally compare your learning curve with the learning 
 curve on page 132 of your text. Tell whether it is the 
 same or a different type of curve,- and what makes it 
 either alike or different. 
 
 III. The Threshold in Estimating Weights. 
 First Part 
 
 It often hai)pens in life that you have to apply your 
 body to something multiple which, from case to ease, 
 becomes eitlier increasingly difficult or increasingly easy. 
 With increasing difiSculty, it is clear that you should 
 then pass thru some cases where you say "It is more or 
 less s'uess work." Those cases you call the "threshold." 
 You are, so to speak, passing- out of the chamber of suc- 
 cess. But you have not yet left that chamber behind 
 
THRESHOLD IN ESTIMATING WEIGHTS 17 
 
 you, — you are still "on its threshold." Passing to fur- 
 ther eases in the same direction, it becomes "a mere 
 guess." The chamber of success now is at a distance: 
 You have left behind you the threshold, figuratively. 
 
 Going from ease to case in the other direction, too, you 
 pass thru the threshold. You then say " It no longer is 
 a mrrc guess; but there is no certainty yet." 
 
 Do not, then, think of the threshold as a dividing line. 
 It is a dividing region, just as the threshold of your bed 
 chamber is not an abstract geometrical line, but a board 
 of considerable width, enough to remain standing on. 
 
 The threshold, in a more abstract geometrical sense, 
 has often been defined statistically by the numerical 
 probability of an error being just one-half, that is, the 
 probability of success being equal to that of failure. 
 This by the wa^ You will not, in this demonstration, 
 have to consider further this abstract threshold. 
 
 Yqu will now demonstrate in the concrete what is 
 meant by the threshold. You will make the human race 
 apply itself to estimating weights. For convenience's 
 sake you will here restrict yourself to that part of the 
 human race made up of your partner and yourself. You 
 need not hesitate thus to restrict your demonstration. 
 You are not here expected to make a contribution to 
 science by discovering Jhe exact location of that thresh- 
 old — that has been found out already with sufficient ac- 
 curacy l)y others. 
 
 You will then here form a closer partnership than be- 
 fore with your partner. You will ask your partner to 
 lift one after another the seven wooden weights, which 
 look very much alike, and arrange them ciuickly (in fif- 
 teen or twenty seconds) in an orderly series from the 
 heaviest to the lightest. Immediately your partner will 
 
18 PSYCHOLOGY DEMONSTRATIONS 
 
 ask you to lift them in succession and make any change 
 in their order that seems to you necessary. Then again 
 your partner, and again you, and again your partner, 
 and so on alternately, will do the same until you both 
 reach an agreement. 
 
 Do not complain to the instructor that you can not 
 reach an agreement, that the one of you regards a weight 
 as heavier which the other regards as lighter. There 
 are many situations iti life where we absolutely have to 
 agree. This is one. You should have selected a more 
 congenial partner. It is now too late. You have to 
 make the best of your choice. You have to compromise. 
 How — that is your own business. 
 
 As soon as j'ou both have settled the matter and the 
 weights appear in what you both regajxl as the final ar- 
 rangement, ask for a balance and weigh each weight in 
 full grams, writing the numbers down in a single column 
 in your note book, carefully preserving the order -from 
 the heavy to the light. 
 
 "In full grams" means "not using fractions." Use 
 the nearest integer. The "nearest," jiot the next higher 
 invariably nor the next lower either. 
 
 These seven numbers now form six ratios, the first 
 and second number the first ratio, the second and third 
 number the second ratio, and thfis to the sixth ratio. 
 
 Now rewrite these ratios in terms differing by 1. This 
 can easily be done by subtracting the "denominator" 
 from the "numerator" and dividing by the difference 
 thus found both the "numerator" and the "denomina- 
 tor." For example, if you have 111 grams and 99 
 grams, the difference is 12. Dividing 111 by 12 and tak- 
 ing the "nearest" integer gives you 9 (because 111 :12 is 
 
THRESHOLD IN ESTIMATING WEIGHTS 19 
 
 9%;_.. And dividing 99 by 12 gives you 8. So the 
 ratio for this case is 9 : 8. 
 
 After having written in a column the six ratios in 
 terms differing by 1, mark all those ratios with a cross 
 which are wrong, that is, in which the smaller term pre- 
 cedes the larger term. Suppose you tind then only one 
 marked with a cross; record that ratio as surely being 
 "within the region of the threshold." 
 
 Suppose you find two or more ratios marked with a 
 cross; select the one that has the smallest terms. For 
 example, if the "wrong" ratios are 21 : 22 and 53 : 54, 
 record 21 : 22. It is clear — is it not ? — that if you, the 
 whole human race co-operating, already make a mis- 
 take in the case of the weight difference of one twenty- 
 first,, your estiniation is already here becoming more 
 or less guess work and will be still more so with a 
 difference of one fifty-third. So you record, if you 
 record any one ratio, rather that with the smallest terms 
 differing by 1. The ratio with the smallest terms is the 
 most interesting one from the practical point of view. 
 
 Thus you have made a concrete demonstration of the 
 threshold of the human race in estimating weights that 
 look alike. Never mind that your result is not very 
 accurate. How to proceed in order to get a very ac- 
 curate measurement, is a question which does not now 
 and here confront you. 
 
 But suppose that none of the six ratios was wrong. 
 Well — that was bad luck for you. You thereby learn 
 that in psychology demonstrations it frequently hap- 
 pens that the "errors" are the only events that are 
 interesting. Do not conclude that you are with your 
 weights already beyond the threshold region, on the 
 
20 PSYCHOLOGY DEMONSTRATIONS 
 
 side of certaintj' of judgment. Believe the author of 
 this book when he tells j'ou that you are not. 
 
 Of course, it does not follow that therefore you mrst 
 intentionally now and then apply yourself in the wroncj 
 way. But it does follow that you must not bj' any kind 
 of trick or jugglery (for example, by secretly weighing 
 and marking the weights in advance) try to cheat the 
 instructor. In sucli a ca.se you do not cheat the instruc- 
 tor, but you cheat yourself. You then, having no er- 
 rors, have to ask the instructor to give you a new set 
 of seven weights, and you and your partner have to 
 make the demonstration all over, until you have some 
 error. 
 
 If, however, you have used no tritk whatsoever, and 
 nevertheless your ratios are all right, you simply have 
 had had luck (that often happens in this world) and 
 you have to ask the instructor for a different i^et of 
 weights and make the demonstration all over. 
 
 Hecond Part 
 
 The instructor will now give you two wooden weights 
 considerably differing in size. You notice that these 
 weights have holes on top. You will then fill one of 
 them with scraps of lead until your partner and you 
 admit that they are now as equal in weight as you caiT 
 mutually agree on. 
 
 Remember that nobody has asked you to use any 
 trick, for example, to close your eyes and balance the.=e 
 weights on the tip of your nose. You apply your body 
 to these weights as naturally as you apply it to pick- 
 ing up a chair in one corner of the room and setting it 
 down in another corner. Use only one hand always. 
 
THRESHOLD IN ESTIMATING WEIGHTS 21 
 
 When you liave filled one of the holes to the top, 
 do not hesitate to put a little paper box on the top to 
 receive more of the lead scraps. After making the 
 weights equal, you weigh them on the balance in full 
 grams and compute the ratio in terms differing by 1. 
 
 Now ask your partner the question: "Is this ratio 
 (much or little) above or below 1;Jie threshold which we 
 found in the fii-st part of this demonstration ? ' ' — Explain 
 to your partner what is meant by "above" or "below" 
 the threshold. "Above" means in this case that the 
 ratio terms are smaller than those of the threshold. 
 "Below" means that the terms are larger. 
 
 Further ask your partner what his experiences (be- 
 fore and after) were when, in the middle of a long 
 journey made without changing the tpain, the locomo- 
 ti-^'c was taken off and replaced by a much stronger 
 acting engine. Then ask him whether he suspects .that 
 his muscle contractions applied to the one and to the 
 other weight, might be comparable to those two locomo- 
 ti^'es, and whether his experiences might be comp.arable 
 to those on that train before and after the change of 
 locomotives. Could he have had similar experiences if 
 instead of a change of locomotives something had hap- 
 pened to the train itself? What? Ask your partner 
 to read what he finds on page 148 of his text on the 
 kinesthetic sense. Ask him whether that helps him to 
 talk about his experiences with the weights. 
 
 What happening to the train itself would be directly 
 comparable to filling the holes with lead scraps? And 
 what are (1) the experiences which would then be 
 equalized on your railroad journey, and (2) those ex- 
 
22 PSYCHOLOfiY DEMONSTRATIONS 
 
 periences which are then equalized on your weight lift- 
 ing enterprise? (Refer- to page 148 of your text.) 
 
 Try whether you can avoid "changing the locomo- 
 tives" by closing your partner's eyes and hanging each 
 weight a little while from a string looped over his out- 
 stretched finger instead of permitting him to pick up 
 the weight. 
 
 Finally read in your text all the references whic-h 
 you find in its index under "illusion" and tell what 
 relation they have to the second part of this demonstra- 
 tion. 
 
 IV. The Sound LocaUzituj Reflex. 
 
 You want to become familiar with the fact that your 
 basic action equipment, received thru heredity, is your 
 equipment with reflexes. Get then a concrete idea of 
 the sound localizing reflex by finding out whether your 
 partner's success in using sound localizing hahils is 
 conspicuously improved by the additional function of 
 this reflex. Compare page 180 of your text. 
 
 Recall what you find on page 194 of your text about 
 the dimension or dimensions of this reflex. 
 
 You are going to u.se telephone clicks. Wi'l your 
 partner be able to use the localizing habit described on 
 page 194 of your text? The existence of what other 
 localizing habits seems probable to you? P,or example, 
 do you believe that you might possess a habit like this : 
 Calling a rather strong click "front" in.stead of strong, 
 railing a rather weak click "back" instead of weak, 
 and a medium click "above"? 
 
 Remember during the whole demonstration that you 
 want to discover if, in comparison with that success 
 
SOUND LOCALIZING REFLEX 23 
 
 which depends on his habits alone, the reflex improves 
 your partner's success in localizing. Remember that 
 the improvement can be demonstrated only by the per- 
 centages of errors, and that, if there are no errors at 
 all, there will be no percentages to compare. Tell your 
 partner, therefore, that you do not intend to prove that 
 he is clever enough or unable to get thru without errors, 
 that on the contrary the errors are the only valuable 
 part of the demonstration. Tell him that you have, 
 therefore, no objection to his reciting to himself, silent- 
 ly, anything he may wish to, while you are giving the 
 clicks. 
 
 Ask the instructor to give you a printed record blank. 
 On this blank you find 81 squares in nine rows and nine 
 columns. The rows correspond to the nine stimuli Right, 
 Right-Back, Right-Front, Back, Above, Front, Left- 
 Front, Left-Back, and Left. Inform your partner that 
 these wiil be the only stimuli ever given and that, there- 
 fore, he need not ever reply in any words but these. 
 The judgment pronounced by your partner will be re- 
 corded by you by making a little cross in the proper 
 column, but exactly in that square of the column which 
 is located in the row corresponding to the stimulus 
 given in that case. The question of "right or wrong" 
 does not arise in this recording. 
 
 Remember, you never want to surprize your partner, 
 but you prepare him by a "Ready" signal. Being sure 
 that your partner's eyes are closed, you set the tele- 
 phone, hit the key hard with your finger so that the 
 noise of hitting serves as "Ready" signal, and two or 
 three seconds later raise your finger. The break in the 
 electric current causes the click in the telephone. Your 
 partner pronounces his judgment, and you record it. 
 
24 PSYCHOLOGY DEMOXSTRATIOXS 
 
 Continue this, irregularly varying the location of the 
 telephone, until you have ten records in each of the nine 
 rows, — a total of 90 judgments. 
 
 Never repeat the click, even tho your partner may tell 
 you that he was not sure of its location. Recall to him 
 that it is his very error, and not his being sure, that in- 
 terests you. 
 
 Your partner will then ask for a second record blank 
 and will make the same ' demonstration on you. You 
 may, however, both of you, divide the whole task and 
 alternate two or three times, being now subject, now 
 demonstrator, now subject again, and so forth. 
 
 Now translate the records from your squares into the 
 followiiifj summaries. 
 
 Lefts (L, LI", LB) regarded as Rights (a, KB, KF) times. , „ , , 
 
 ^ Total. 
 
 Bights CE, KB, E.F) rpffarded as Lefts (L, LF. LB) times. 
 
 Fronts (T, EF, LF) rpgarded as Backs (B, EB, LB) or Above .. times, -j 
 
 C Total 
 Backs {B, SB, LB) regarded as Fronts (F, EF, LF) or Ahove. .times, f 
 
 Above called Fronts CF, EF, LF) or Backs (B, EB, LB)., times. 
 
 Above called Eights (E, EB, EF) or Lefts (L, LB, LF).. times. 
 
 Above judged correctly times. 
 
 Then draw a final conclusion as to whether the reflex 
 has shown its influence or not. Also state what your 
 record shows, if anything, concerning the "habit ques- 
 tion" raised above in the third paragraph of this chap- 
 ter. 
 
 V. The Reflex of Adjusting the Eyeball. 
 
 You know that it has an effect on you, calling forth 
 your bodily reactions, when the Other-One turns his 
 eyes on you. In this respect we can speak of a local- 
 
ADJUSTING THE EYEBALL 2,J 
 
 iziuji' action performed by the Other-One with his eyes. 
 But this is a localizing habit developed out of an adjust- 
 ing reflex. Read pages 188-189 and 193-194 of your 
 text. 
 
 The study of the sense organs as such is not neces- 
 sarily a part of the psychologist's task. The physiolog- 
 ist must study all the sense organs. The psychologist 
 studies them only in so far as his definition of psychology 
 requires it. (Different psychologists differ in their def- 
 initions.) Read what you find about the definition of 
 psychology in your text on pages 8-11, 405-408, ■ 421, 
 422. Read also the reference you find in the index of 
 your text to "higher senses". Do you see, then, any 
 reason for familiarizing yourself with the adjusting re- 
 flexes of the organ of sight? What is the reason? 
 
 The reflex of adjusting the eyeball in its bearings is 
 necessitated by the fact that the sensitive cells of the 
 retina are very close together only in the central region. 
 Things with small details (especially printed matter) 
 can therefore act properlij as stimuli only in that cen- 
 tral region. That is the reason why the eyeball is con- 
 stantly moving. 
 
 But it is a mistake to think that the stimulation is 
 effective during the motion of the eyeball. Nature has 
 made a provision whereby the excitation coming from 
 the retina during eye motion is completely deflected 
 (probably by the very nervous current causing the con- 
 traction of the eye muscles), so that there is virtually 
 no reaction to the retinal excitation. (Understand what 
 "deflection" means by using the index of your text.) 
 
 Think- it over and answer the question whether the 
 loss of this reaction during eye movement is a serious 
 
26 PSYCHOLOGY DEMONSTRATIONS 
 
 one, or — possibly — even an advantage. What could 
 your partner call a thing stimulating his retina during 
 the eyeball's motion? "Would that name be of any 
 help to him or to you in getting along in this world? 
 Remember, in answering these questions, that the eye- 
 ball is incapable of moving with a small angular ve- 
 locity; that it always moves with a very great angular 
 velocity. 
 
 Further ask yourself of what significance the loss of 
 the reaction to retinal stimulation during eye movement 
 is for the theories, rampant until twenty years ago, 
 which explained the great beauty of a smooth curve in 
 comparison with an irregularly bent sygzag or scrawl 
 by the greater ease of following one of these lines con- 
 tinuously with the seeing eye. Why are these theories 
 not found in recent books? 
 
 When your partner reads, he reacts only to the stim- 
 lations occurring while the eyeball stops. Demonstrate 
 these stops by asking your partner to read — very slowly 
 and aloud — from an easy text about twelve or fifteen 
 consecutive lines. Close to his text on the right you 
 place a mirror and watch your partner's right eye in 
 this mirror. Let your partner rest his head against a 
 support which will virtually exclude head movements. 
 ]\[ake a pencil mark every time an eye movement oc- 
 curs ; but do not make a mark for the longer movement 
 leading from the end of one line to the beginning of the 
 next. 
 
 It has already been said that you must make your 
 partner read aloud, in order that you may be sure 
 that he is really reading, — and reading properly, that 
 is, in the way ijou want him to read. Tell him to make 
 
ADJUSTING THE EYEBALL 27 
 
 a very conspicuous pause at the end of each line, but to 
 make no conspicuous pauses at the punctuation signs. 
 
 If the number of eye movements in a line is n, what 
 is the number of stops? Write down in your note book 
 the number of stops which occurred in each of the lines 
 read. Also measure and write down the length of the 
 lines. Why the latter? Also determine the average 
 number of letters (and spaces) for each stop. 
 
 Now cover the right and the left side of a printed 
 line with paper (fastening it with clips), leaving un- 
 covered only as many letters (and spaces) as you j'.st 
 found by computation. Choose as the center of this 
 group of letters a conspicuous narrow one, for example, 
 a f. Then tell your partner to iixate with his eyes this 
 central letter, and, ivhile keeping his eyes perfectly still, 
 to name all those letters which are clearly recognizable. 
 
 What significance does it have if he names all or not 
 all of the letters exposed? Does it explain any facts 
 which you are familiar with or have heard about in 
 connection with the manner people read? 
 
 Do you know anything like it in human life outside 
 of reading, even outside of the use of the sense of sight ? 
 Do you find anything like it mentioned on page 227 of 
 your text ? What is it ? 
 
 VI. Reversing One of the Visual Localizing Reflexes. 
 
 You should first understand the purpose of this dem- 
 onstration by reading pages 183 and 184 of your text. 
 Ask the instructor to give you the card pictured on 
 page 184 and a large total reflection prism, — large 
 enough to look thru with both eyes at once. Mount the 
 card on the table and the prism before your partner's 
 
28 psycnoLOGY demonstrations 
 
 eyes so that the card, when your partner looks at it 
 thru the prism, appears perfectly natural with the num- 
 bers from 1 to 16. 
 
 A similar procedure would consist in using a mirror 
 instead of the prism. But that would have the enor- 
 mous disadvantage of forcing your partner to "look" 
 (at the ob.ject handled) in one direction, toward that 
 mirror, and to "handle" the ob.jeet seen in an entirely 
 different direction, where it really is. You would then 
 7iot only reverse your partner's localizing reflex in a 
 siutrle direction, hut force him to acquire simultaneously- 
 a coitiplexihj of other very queer habits. Such a com- 
 jdexity would confuse you. As a matter of fact, a total 
 reflection prism is nothinjr but a mirror, but it is a mir- 
 ror which does not serve the purpose of looking at your- 
 self, but of looking at other things icithout ireaking the 
 line of sight angularlg. 
 
 Now f:ive your partner the sixteen little squares well 
 shuffled, not in any order. Wait till the hands on your 
 watch have a convenient position and say "Start". 
 
 Do not acceijt your partner's work until the little 
 squares have Ijeen distributed with sufficient accuracy 
 so that each is properly placed, without conspi-uously 
 encroaching upon the area belonging to its neighbors. 
 Then mark at once the time and reduce minutes and 
 seconds all to seconds. 
 
 Now give your partner a chance to put 3'ou to the 
 same task. After that he must distribute the little cards 
 again, you again, and so forth. Stop this finally when 
 you notice that the time of performing the whole work 
 drops from the preceding case to this last only quite 
 inconspicuously, or even rises, sliglitly by accident. 
 
REVERSING ONE OF THE REFLEXES 2!) 
 
 Quite aside from having demonstrated the tenacity 
 of the original reflex, you have again demonstrated the 
 possibility of breaking up a reflex, substituting for the 
 original muscular action a different muscular action. 
 And j^ou have again the material for the construction 
 of the learning curve. Show your partner's learning in 
 a graph similar to the one you made in the second dem- 
 onstration and follow again the instruction given in the 
 last paragraph of the second demonstration. 
 
 YII. Some Habits of Rhythm. 
 
 This demonstration has to be continued for at least 
 two months, altho it takes only a few minutes each week. 
 It must therefore not be begun too late in the course. 
 
 Your partner may have "rhythm". If you ask him 
 and he answers in the affirmative, ask him further ' ' what 
 rhythms" he has. If he does not understand your ques- 
 tion, read to him page 338 of your text. It is not very 
 probable that he will assert that he already possesses 
 the 5-stroke or the 7-stroke rhythm. Therefore yoa will 
 do best to choose for your demonstration of the acquisi- 
 tion of rhythm habits, the 5-stroke and the 7-srroke 
 rhythms. JIake an agreement with your partner set- 
 tling the question which of you shall learn the .5-stroke 
 rhythm and which the 7-stroke rhythm. 
 
 In order to be able to demoiastrate in the cud that 
 your partner has acquired a (weaker or stronger) 
 rliythm habit, you must measure how iccU he can per- 
 form a certain act, which later will depend or, the aid 
 of that rhythm habit, at the present time without that 
 rhythm habit. You will then later also measure Jiow 
 well he can perform that same act (which he will not 
 
30 PSYCHOLOGY DEMONSTRATIONS 
 
 practice meanwhile), and the difference will toll you 
 whether he has acquired, weakly or strongly, that 
 rhythm habit. 
 
 Suppose your partner has chosen to be trained in the 
 7-stroke rhythm. You then give him the following ini- 
 tial test. 
 
 You make him stand before a large wheel (the Avheel 
 placed at your disposal is of three feet diameter) with 
 its axle in a horizontal position perpendicular to his 
 line of regard. He looks at the circumference of the 
 wheel and sees there large digits appearing from above 
 and passing away below. You notice that only the digits 
 1, 2, 3, 4, 5, 6, 8, 9 are used and that they appear at 
 random, without any order whatsoever. The reason 
 why and 7 are omitted is this. You will later ask your 
 partner to read the digits aloud as they appear, and 
 to pronounce them very pointedly. This can be done 
 only with monosyllabic words; and therefore the bisyl- 
 labic digits are left out. 
 
 Before the wheel you place a screen with a window 
 so that most of" the wheel is never visible, and that never 
 more than two digits are simidtaneously visible thru the 
 window. 
 
 Now you adjust the speed of the electric motor which 
 drives the wheel. You increase the speed of the wheel 
 while your partner is reading off each digit at the mo- 
 ment Avlien it disappears behind the bottom frame of the 
 window. As soon as you have reached (be a little pa- 
 tient in doing this!) such a speed that your partner be- 
 S'ins to find it impossible to read off each digit correctly, 
 you decrease the speed again a little. Thus you have 
 
HABITS OF RHYTHM 31 
 
 found the greatest speed at which your partner can read 
 off these digits pointedly without making any errors. 
 
 Now you are ready for the real test. Before your 
 partner, between him and the wheel, you put a solid 
 little table or wooden stand, just high enough for him, 
 while he is standing, to place his hand on conveniently. 
 You then give him a short-handled and rather heavy 
 rubber hammer to hold in his hand, and tell him to hit 
 the table with the hammer on reading off every seventh 
 digit without letting this hammer work in any way in- 
 terfere with the manner or the correctness of reading 
 off the digits. Seat yourself a little sidewise and to the 
 rear where your partner can not see you or your mo- 
 tions distinctly. Count silently so that he can not hear 
 you from 1 to 7, beginning with each one of his hammer 
 strokes. In both your hands you hold little automatic 
 registering machines, so-called tallying registers. "When- 
 ever he hits correctly after you have said to yourself 
 "7", you press the button in your right hand. When- 
 ever he makes an error, not hitting at the right moment 
 or doing it at a wrong moment, you press the button in 
 your left hand, and at the time of his hitting begin 
 with "1" a new silent counting. 
 
 Continue this test for five minutes. In order to do 
 that conveniently, you start, at the moment when your 
 partner begins his hammer and reading work, an inter- 
 val timer set to ring after five nlinutes. 
 
 During the test, while your chief attention must be 
 paid to pressing correctly the buttons in your hands, 
 you must give enough secondary attention to your part- 
 ner's reading to help him to be aware of it if he should 
 fall into reading slovenly, leaving out digits which ae- 
 
32 PSYCHOLOGY DEMONSTBATIONS 
 
 tually appear, or reading the digits wrongly. Discount 
 a merely occasional lapse of speech such as — maybe — 
 pronouncing sic instead of six or fro instead of four. 
 But do not permit real and serious errors in reading, for 
 your whole test is based on the presumption that your 
 partner reads off the digits correctly. "Errors" are 
 permitted and valuable in this demonstration only in so 
 far as the rubber hammer may strike at the wrong digit. 
 
 At the end of the five minutes look at your tallying 
 registers and record carefully the numbers they tell you 
 for correct strokes and errors. Also ask your partner 
 (and write down) whether he considers this hammer and 
 reading work easy or difficult to perform correctly. You 
 would better ask him this question before you have told 
 him the numbers which you have found on your tally- 
 ing registers. 
 
 Your partner will now test you in the same manner, 
 with this difference only, that he will tell you to hit the 
 table with the hammer on reading off every fifth digit. 
 
 These tests now will not be repeated for at least two 
 months. Meanwhile you wijl both regularly five minutes 
 (neither less nor more) per week take an exercise train- 
 ing you in the rhythm habit which you have chosen. It 
 is essential that this exercise be taken faithfully. Be- 
 gin today. 
 
 Your partner, training for the 7-stroke rhythm, will 
 proceed as follows. He will stand before the frame de- 
 scribed on page 347 of your text. He will take the rul)- 
 ber mallet in his right hand (we suppose him to be right- 
 sided, — if his left side is his better side, all rights and 
 lefts must be exchanged) and hit the button on the left. 
 He carries out the rebound and makes a preparatory 
 
HABITS OF RHYTHM 33 
 
 movement for doing the same thing toward the right 
 button. After the next preparatory movement, for the 
 left button, however, he "changes his mind" by adding 
 a further preparatory movement leading his hand thru 
 a short curve (a quadrant) to a place a little above the 
 center of the frame. This finishes the whole group of 
 seven motions. There is no counting of any kind nec- 
 essary in this performance, either by your partner or 
 by you. 
 
 After the horizontal performance your partner now 
 does the same in the vertical direction. The final curve 
 leaves his hand a little to the right of the center of the 
 frame. He goes again thru the horizontal performance, 
 again thru the vertical performance, and so on, until 
 you tell him that his five minutes are over. Watch his 
 motions while he exercises, and if he does not do the 
 work right, correct him. You are responsible for his 
 learning to do the work right. See to it that he does 
 7iot make any pauses between his motions, especially not 
 after the, quadrant, or extend or reduce the time for any 
 of the seven motions so that it becomes very different 
 from the duration of any of the other six. Each of the 
 seven motions should with fair approximation be of the 
 same duration. But no exactness of equality of the 
 duration is desirable. Let him work naturally. By fair 
 approximation to the same duration is meant only that 
 none of the seven motions must ever last even approxi- 
 mately twice as long as any of the other six. 
 
 After your partner has finished his five minute exer- 
 cise, he makes you take your five minute exercise. You 
 go thru the performance consisting of five group mo- 
 tions, which is described on page 347 of your text. Both 
 
34 PSYCHOLOGY DEMONSTRATIONS 
 
 you and your partner take your five minute exercises 
 regularly once a week for at least two months. Then 
 you are ready for the final test. 
 
 In the final test you proceed as in the initial test. You 
 put your partner before the wheel and make him read 
 aloud the digits and hit the table with the hammer on 
 reading off every seventh digit, for five minutes. 
 
 Compare the numbers given by the tallying regis- 
 ters in your hands with the numbers obtained in the 
 initial test. The difference is an indicator of the strength 
 of the rhythm habit which your partner may have ac- 
 quired during the exercises of the last two months. Also 
 ask your partner how easy or difficult he considers the 
 combination of his hammer and reading work now. 
 
 VIII. The Accommodation Reflex Used for a Purpose 
 Other than Adjustment of the Eye. 
 
 Read what you find on pages 189 and 190 of your text 
 on the reflex which flattens the lens, and on page 244 on 
 the use of the accommodating apparatus for the pur- 
 pose of "localizing in more or less depth" (by habit or 
 by reflex). 
 
 For this demonstration you use an apparatus designed 
 by Hering (of whom you have heard in connection with 
 color vision). It is essentially a box-like frame which 
 has a small object (for example, a bead) suspended as 
 a mark at about the middle distance from front to back. 
 Your partner looks thru a horizontal slot steadily at this 
 mark. The slot is so arranged (for example, by dupli- 
 cating it, one behind the other) that your partner can 
 see neither the floor nor the ceiling of the "box", but 
 easily a little space above and below the mark. 
 
A REFLEX USED FOR A NEW PURPOSE 35 
 
 You insist on your partner keeping one eye securely 
 covered and out of function. 
 
 Now you give a "Ready" signal and two or three sec- 
 onds later drop a bead or other object similar to the 
 suspended one. There are four holes in the roof of the 
 box, two in front, two in the .rear of the mark, which 
 you must use at random for dropping. These holes are 
 arranged so that, no matter which of them ,you use, the 
 object dropped will appear to your partner at about the 
 same distance sidewise from the mark. You ask your 
 partner whether it was farther or nearer from him than 
 the mark. According to his answer you write in your 
 note book, in a column, case after case, either P or N 
 and add to it a cross if the answer was wrong, a ring 
 if the answer was right. 
 
 It is advisable to vary a little the size of the objects 
 dropped. "Why? 
 
 Never repeat a case on account of being told by your 
 partner that he does not feel sure. Call his attention to 
 the fact that you are not trying to find out how clever 
 he is, and that he ought to have found out by this timft 
 that the errors recorded in psychology demonstrations 
 are often the only really valuable part of the procedure. 
 
 When you have twenty-five cases, stop. Take a rest 
 by letting your partner work with you in the same man- 
 ner. 
 
 Then proceed again with your partner as you did at 
 first, but with this difference that now you do not drop 
 the object, but lower it slowly on a fine black thread, 
 making sure that you go below the level of the mark and 
 that you expose the object to your partner's eye (one 
 
36 PSYCHOLOGY DEMONSTRATIONS 
 
 eye) between two and three seconds. Finally your part- 
 ner does the same with you. 
 
 Now compare the number of errors you got in drop- 
 ping and in lowering. How do you explain the differ- 
 ence? 
 
 After this both you and your partner make another 
 series of twenty-five drops (remember "drops only") 
 each, but this time with both eyes open. How many 
 errors do you find now? Do you think that the facts 
 found warrant the belief that another adjustment, men- 
 tioned on page 244 and also on page 188 of your text, 
 plays a role here ? Do not answer rashly ! 
 
 If this adjustment (the angle of convergence) is fol- 
 lowed by an action of "localizing in more or less depth," 
 what is the direct stimulus of this action of localizing 
 in depth? Look to pages 148 and 149 of your text for 
 a suggestion. 
 
 Can the sensory-motor function hinted at in the last 
 two paragraphs be the explanation of the facts which 
 you observed in dropping things before your partner 
 while he had both eyes open? If so, why so? If not, 
 why not? 
 
 Could the habit of "localizing in depth" described 
 on page 258 be the explanation of the facts discovered 
 by dropping things before your partner while he had 
 both eyes open? If so, why so? If not, why not? 
 
 IX. A Species of Motor Condensation in the Nervous 
 Functioning. 
 
 First examine your partner and, if necessary, teach 
 him all that is said on pages 220-222 of your text. You 
 find it said there that "special conditions delay the re- 
 
MOTOR CONDENSATION 37 
 
 action" to each of two reflex responses; and finally 
 neither of them occurs, but instead of them the pro- 
 nunciation of a certain word. This ' ' delay ' ' might make 
 you feel inclined to become shaky in your conviction 
 that "states of consciousness are not to be regarded as 
 causes in science." A friend believing otherwise might 
 urge you to admit that "the delay is caused by your 
 partner's thinking and that that thinking then becomes 
 the real cause of his later pronouncing that word. ' ' We 
 shall help you here to defend your position. 
 
 It is really only a figure of speech when we say an 
 action is delayed. A reaction cannot be delayed, for 
 
 the nervous system is not — (look up in 
 
 the index of your text the items "afferent and efferent" 
 and find in the text the words with which to fill in this 
 blank), but a system of conductors. . No stream of excita- 
 tion can enter the system without a like stream passing 
 out during the time. The ' ' delayed reaction ' ' only means, 
 really, that you cannot notice any reaction of which you 
 are sure that it belongs to that stimulation. This means 
 that the muscular reaction is so widely scattered that 
 it simply becomes a part of what the physiologists call 
 "the general muscle tonus". 
 
 ' ' But why is it thus scattered 1 Why does the nervous 
 current, instead of going mainly to the (reflex) motor 
 point corresponding, go in the main to innumerable 
 scattered motor points?", asks your friend. The answer 
 is simple enough: Because some preoccupation (compare 
 the pages from 91 to 97 of your text) has been estab- 
 lished which opens up the paths thus scattering the cur- 
 rent. Such a preoccupation can easily be established, 
 for example, in accordance with our speech habits, by 
 
38 PSYCHOLOGY DBMONSTEATIONS 
 
 somebody saying .authoritativejly "No, no,' — don't, 
 don't;" or by your instruction given previously to your 
 partner to the effect that you care nothing about the 
 direct localizing reflex movement. The current will then 
 go, in the main, to the higher center serving the repro- 
 duction of the words of instruction and thence to the 
 muscle systems pronouncing these words or to the gen- 
 eral muscular system, in the latter case merely adding 
 imperceptibly to the general muscle tonus. 
 
 But these muscle contractions, belonging to the speech 
 functions or to the general muscle tonus, are themselves 
 of the nature of (kinesthetic) stimuli (compare what 
 you find on pages 361 and 362 of your text) insuring 
 a continuation of the streaming of excitation thru tl\> 
 nervous system, again resulting in either the pronun- 
 ciation of such words or an addition to the general mus- 
 cle tonus. And this streaming of excitation more or 
 less scattered thruout the nervous system may go on for 
 seconds or minutes (or even hours) without bringing 
 about any muscle action which you would regard as 
 worthy of being called "the" reaction to the initial 
 stimulus. 
 
 Gradually, however, a change may come about in the 
 streaming within the neiT^ous system. It may be that 
 from the beginning the intensity of the flux was a trifle 
 stronger in a certain motor direction than in all others. 
 By the law of deflection, (compare pages 102 to 106 of 
 your text) then, the flux in that direction must become 
 stronger and stronger and very strong, if you only give 
 it time enough. Or a second stimulus occurs and estab- 
 lishes a current in a certain direction (by reflex or habit) 
 which now gradually draws the other currents into it- 
 
MOTOR CONDENSATION 39 
 
 self. Thus, finally, a definite action occurs which seems 
 to have such a clear logical relation to the initial stim- 
 ulus, that everybody calls it "its reaction", merely 
 adding that ' ' it was delayed. ' ' 
 
 The delayed reaction thus is in no way mysterious, 
 for the simple reason that it is not in reality a delayed 
 reaction. It is mysterious only to those who think of a 
 nervous process as if it were like a ball ("one" ball, 
 "the impulse") running along a bowling alley, perhaps 
 striking the walls here and there and very soon reach- 
 ing the ten-pins. But if there should be an elevated 
 ridge made of inclined planes and crossing the alley, the 
 ball may run up and stay on the ridge a long time in 
 delicate equilibrium. A little later another ball may 
 get lodged on the ridge, and another and another. But 
 after a considerable time (delay) a naughty boy ("the 
 will") who has no respect for the laws of "mere mat- 
 ter" comes and kicks one of those balls against the 
 others with the result that they all run off the inclined 
 plane and toward the ten-pins. This antiquated con- 
 ception of the brain as a tank (or, here, ridge) where 
 things (knowledge) may be stored for a long time until 
 a mysterious force drains the tank, is still rather pop- 
 ular. But modem biological thought is in the direc- 
 tion of regarding the nervous system as what we called 
 it, a system of conductors and nothing else. 
 
 Returning now to what you want to demonstrate, you 
 are going to touch your partner with two compass 
 points, having previously instructed him to respond with 
 a single reaction, either that of saying "one" or that 
 of saying "two". You are thus going to demonstrate 
 that species of motor condensation of the nervous func- 
 
40 PSYCHOLOGY DEMONSTEATIONS 
 
 tioning which is the most common species of motor 
 condensation, — so-called space perception. Ask your 
 partner whether he understands clearly what your text 
 means by sensory condensation and motor condensa- 
 tion. Make it still clearer to him by referring to the 
 figures and the descriptive words on pages 224 and 225. 
 
 Then draw in your note book nine vertical lines, leav- 
 ing between them eight blank columns. The first, third, 
 fifth and seventh of these columns you fill in with the 
 consecutive numbers from 1 to at least 20. You will 
 soon find out bow far you will have to go beyond 20. 
 These numbers really stand for one-sixteenth, two-six- 
 teenths, and so forth, of an inch. 
 
 You now have the choice between two methods. You 
 may proceed thru the column in regular order and first 
 touch your partner with two compass points 1 sixteenth 
 of an inch apart, then with two points of 2 units in- 
 terval, then of 3 units interval, and so forth. But in 
 that case you have to touch him now and then, very 
 irregularly, with one point only; and if he should say 
 "two" even in such a case, you have to tell him that 
 he has spoiled the whole procedure and that everything 
 (the whole column) has to be done over again from 
 the beginning, your record thus far obtained being 
 destined for the waste basket. 
 
 If you and your partner do not like that, you have 
 to choose the second method, in which the distances 
 written in the column are used in quite irregular or- 
 der. But let us suppose you succeed in training your 
 partner never to say "two" when there is the least 
 doubt about there being two. You can then use, and 
 we assume now that you are going to use, the first 
 method. 
 
MOTOB CONDENSATION 41 
 
 You already know about the necessity of a "Ready" 
 signal before giving the stimulation. When applying 
 the points, remember that you must not apply them in 
 the manner in which a bird pecks at a grain. You must 
 place the two points on the skin with equal pressure for 
 about two seconds, certainly not less than 1^ seconds. 
 You must place them firmly, so that you see the skin 
 indented ; but not with so much pressure that your part- 
 ner 's skin will show the marks even half a minute after 
 removal of the points. Treat your partner as you would 
 like to be treated yourself. 
 
 Choose a region on the inner surface of your part- 
 ner's arm near the wrist. Choose a smooth, fleshy re- 
 gion, not one underlaid with tendons. During the first 
 two series of applying the compass points apply them 
 so that a line drawn thru them would be parallel to the 
 axis of the arm. During the third and fourth series 
 apply the points crosswise. 
 
 During the first and third series pass from the smallest 
 to greater intervals, during the second and fourth series 
 from greater to smaller intervals. Do not stop the first 
 series until you have had at least eight consecutive 
 "two" judgments pronounced by your partner (eight 
 not intermingled with "one" judgments). Write in 
 the proper blank column to the right of each stimulus 
 the judgment "one" or "two." 
 
 You now notice — most probably — in each of these four 
 columns a middle region in which appear both the judg- 
 ments "one" and "two" mingled. Write at the bottom 
 of each column that distance of the compass points 
 which corresponds to the middle of this threshold re- 
 gion. Then take the middle between these two locations 
 
42 PSYCHOLOGY DEMONSTRATIONS 
 
 in the first two columns and also the middle between 
 these two locations in the last two columns. These two 
 values enable you to compare very quickly the threshold 
 lengthwise with the threshold crosswise. Did you suc- 
 ceed in demonstrating what your text says about this 
 matter on pages 221 and 222? 
 
 X. Calling Things Large. 
 
 Place on the table before your partner a large sheet 
 of paper and on it a little scrap of dark colored (per- 
 haps green) pajicr, round, square, or of any irregular 
 shape, and of about two inclies diameter. Tell him to 
 look steadily at one of the corners or at any other 
 marked point of the paper scrap until you have counted 
 200. It is important that he hold his eyes as still as 
 possible during that period. Immediately after count- 
 ing 200 you tell your partner to look steadily at a point 
 on the floor and to say "I see it" as soon as he sees 
 something of the same shape as the paper scrap appearing 
 like a gliost on the floor. At once you make him look, 
 for the same purpose, at a point on the nearest wall of 
 the laboratory room ; and after that on the ceiling ; and 
 after that on the farthest wall of the room. And then 
 you may bold a uniformly colored book cover about six 
 or eight inches before your partner's eyes and tell him 
 to see the "ghost" there. 
 
 If the "after-image" (this is the technical name for 
 such a ghost; compare page 290 of your text) did not 
 last long enough, give your partner a few minutes rest, 
 and then repeat the whole procedure, tiyijig to make 
 him look at the several places in quicker succession, — 
 
CALLING THINGS LARGE 43 
 
 maybe also after counting a little more slowly and 
 strengthening the after-image by lengthening the time 
 of exposure. 
 
 Now ask him how iig he would call the ghost seen on 
 the book cover, the floor, the nearer wall, the ceiling, the 
 farther wall. Tell him, if he talks of its color, that you 
 care nothing about its color, but that you are interested 
 solely in its varying size. 
 
 Ask your partner whether he thinks that there is any 
 reason for believing that the number of sensitive cells 
 which are in a state of excitation has anything to do 
 with calling a thing large or small or larger or smaller. 
 
 No matter whether he answers this last question in 
 the affirmative or in the negative, — ^ask him, further, if 
 he thinks that the Other-One could be misled into calling 
 a small thing large or a large thing small by keeping 
 from him the most, or the more, impressive information 
 concerning the distance which the thing actually is from 
 his forehead. 
 
 For example, if you want to induce the Other-One to 
 accept a dime in exchange for a dollar's worth of gro- 
 ceries, would you be likely to succeed if you thrust your 
 hand, holding the dime, forward toward Ms eyes until 
 they are within a few inches of touching him? 
 
 Or if you want to induce the Other-One to talk of 
 your brother, three hundred feet away, as "being like 
 an ant", would you be likely to succeed if you put 
 your brother three hundred feet away on a busy street 
 where there are plenty of people seen in the space be- 
 tween? 
 
 Or if you want to induce the Other-One to talk of 
 your brother, three hundred feet away, as "being like 
 
44 PSYCHOLOGY DEMONSTRATIONS 
 
 an ant", would you be more likely to succeed if you 
 stand with him on the roof of a sky-scraper, looking 
 over the railing, having put your brother three hundred 
 feet below on the street, with nothing visible in the space 
 hetweenf 
 
 If there were men everywhere floating in the air in 
 the space between, there would be some impressive in- 
 formation concerning your brother's distance. Do you 
 think the Other-One would still talk of him as "being 
 like an ant"? 
 
 Now let your partner formulate the rule by which 
 "information" (right or wrong, but) impressive and 
 believed about the distance, influences the Other-One in 
 calling things large or small (quite independent of the 
 excited area on the retina). 
 
 Was there any reason for thinking that this informa- 
 tion (right or wrong, but) impressive and believed about 
 the distance, was impressive when your partner pro- 
 jected the after-image on the book cover, the wall, and 
 so forth? 
 
 Now ask your partner how he would answer the follow- 
 ing quastion: "WTiat are the two factors on both of 
 which the Other-One's habit of calling things large 
 (larger, smaller, and so forth) depends, provided that 
 both factors exist?" Tell him that both these factors 
 are already hinted at in the preceding pages: one 
 in the paragraph beginning with "Now let your", the 
 other in the paragraph beginning with "Ask your part- 
 ner". Which of these two factors constitutes a simpler 
 and which a more complex habit? 
 
 What relation has this demonstration to what is dis- 
 cussed on page 224 of your text with reference to figure 
 
CALLING THINGS L.\EGE 45 
 
 B ? Apply that figure to each of the tMo factors just 
 hinted at. 
 
 What relation has this demonstration to what is dis- 
 cussed on page 226 of your text in the paragraph be- 
 ginning with "Space"? 
 
 What is the only difference between this demonstra- 
 tion which you made on your partner and that experience 
 with the Other-One which is described on the lower half 
 of page 242 of your text? What is the only difference 
 in the manner of stimulation described there and that 
 used in this demonstration? (How long did you wait 
 between seeing the moon at the horizon and at the 
 zenith?) 
 
 What is said on page 243 of your text about reversing 
 the substitution of one action for another action ? How 
 is this related to the figure on page 124 of your text ? 
 
 Be sure to remember what you have learned in this 
 demonstration in order to make use of it in demonstra- 
 tion XI, and also in demonstration XIV where "size" 
 concerns us in connection with pseudoscopy. 
 
 XI. Wasted Habits of Estimating Space. 
 
 What is that name which is used in your text for both 
 wasted reflexes and wasted habits? Use the index in 
 order to give the answer. 
 
 What does your text say about the habit of o^-eresti- 
 mating or underestimating angles? Look in the index 
 under angles. 
 
 If we call the habit of calling an angle by such a name 
 as "large" or "small" or "nearly 90 degrees" a suh- 
 stituted action, what does that action which is in this 
 
46 
 
 PSYCHOLOGY DEMONSTRATIONS 
 
 case replaced by this substitute consist in? Does not 
 the replaced action consist in calling the thing flat? 
 Look at the thing on page 238. 
 
 What do we mean when we call a thing (any of the 
 things in the accompanying figure) "viewed perspective- 
 ly " ? " Per " literally means ' ' thru " ; and " spect " lit- 
 erally means "seen." What has this meaning of "per" 
 to do with the preceding paragraph? 
 
 
 
 \ 
 k 
 
 Make in your note book carefully an enlarged draw- 
 ing of any one of the things pictured in the figure here 
 and tell your partner to "look thru" that thing. If 
 you have not yet agreed with your partner as to what 
 is meant by the command to look "thru" a picture, 
 return to the last paragraph and reach an agreement. 
 Mark the end points of a properly chosen line in your 
 drawing a and 6 and tell your partner to follow this line 
 in looking "thru" the thing. 
 
 If your partner possesses some perspicacity, he will at 
 once ask you: "Must I look at a first and at b later or 
 at b first and at a later?" Choose one of these two 
 points and tell your partner to arrest his eyes on it and 
 not to continue looking thru the thing until you give 
 
WASTED HABITS OP ESTIMATING SPACE 47 
 
 your permission. Then count silently to 15 and sudden- 
 ly, instead of giving him permisssion now to look thru 
 the thing, cover your drawing with a piece of paper. 
 At once ask your partner to show you, using pencils or 
 matches for this demonstration, how the" line was (or, 
 perhaps, tlie lines were) situated in the space thru 
 which he had hoped to obtain your permission to look. 
 Write down in your note book a description of the situa- 
 tion of that pencil or that match (or, if two or more lines, 
 those pencils or those matches) in some such manner 
 as is indicated by this example, "Pencil going away 
 from me into depth, slanting a little to the right and 
 do^\iiward, " using whenever necessary other terms, 
 perhaps even opposite to those in this sample descrip- 
 tion. 
 
 Now repeat everything spoken of in the last para- 
 graph, with this difference, however, that you now choose 
 the other point as the one on which your partner has to 
 arrest his eyes before being permitted (which he actually 
 is not) to follow the line in looking "thru" the thing. 
 
 You may have to repeat both cases many times before 
 you derive the conclusion that a certain habit of naming 
 (describing) prevails in the one ease and another certain 
 habit in the other. "While you are investigating what is 
 the prevailing habit in each case, you really make a 
 statistical investigation in the one case and in the other 
 case. A single observation is insufficient because habit 
 functions (especially human habit functions) are very 
 much subject to accidental influences (unknown and 
 uncontrollable by you) . 
 
 Now you will have to answer two questions which 
 will inform you whether you have really profited from 
 
48 PSYCHOLOGY DEMONSTRATIONS 
 
 this demonstration and from your study of the text or 
 not as yet. These two critical questions are here directly 
 following. 
 
 If you should hear anybody call one of your two cases 
 a "perception" and the other case an "illusion", how 
 could you defend him and justify his talk ? 
 
 If you should hear anybody call both of your eases 
 "illusions", how could you defend him and justify his 
 talk? 
 
 If you have told your instx'uctor what your answers 
 are and feel quite sure now what it is what your text 
 calls an illusion, proceed with your partner in an en- 
 tirely novel way. Tell your partner to arrest his eyes 
 as long as he wants to on that end point of the line 
 which you have chosen for the start, then to follow the 
 line and to arrest his eyes on the other point again as 
 long as he \vants to. Let him demonstrate now with 
 pencils the location of the lines. Does this case agree 
 with the first above? Or with the second above? Or 
 is it different from both? Perhaps a kind of combina- 
 tion of both? Combined in what manner? Are both 
 points nearer than each other or does time play any role 
 in the judgment? 
 
 Trj' then still another procedure. Tell your partner 
 to proceed from the starting point and to follow the line 
 in looking thru that thing, but to be sure not to arrest 
 bis eyes even for the slightest moment at the point which 
 you have not chosen for the start. Tell him to be sure to 
 slide over the end point into any direction of space. 
 Ask him to demonstrate how the line is then situated in 
 space. Does this case agree with the first ? Or with the 
 second? Or is it different from both? "Whatever it may 
 
^VASTED HABITS OP ESTIMATING SPACE 49 
 
 be, why is it so? That is, in the formation (long ago) 
 .of this habit, what action was substituted for what? 
 
 What general statement would you make, then, con- 
 cerning the question : What is the nature of the class 
 of stimulation which in these demonstrations called forth 
 either the response of saying "This point is the nearer 
 one of the two ' ' or instead of this response the equivalent 
 response of demonstrating with the aid of a pencil the 
 situation in space of a line contained in the picture? 
 "The point not favored by the adjustment of the eye is 
 generally called nearer" — would that statement he the 
 answer? 
 
 You have thus far worked with only one of many 
 drawings any one of which you could have used for the 
 same demonstration and of which you see only seven 
 representatives in your figure. Make in your note book 
 now an enlarged drawing of each of the other six and 
 demonstrate your partner's habits on each one of them 
 in the same manner of procedure just used. Tell in 
 your report why the habits illustrated by all these seven 
 drawings are often — and justly — called (1) illusions of 
 (2) reversible (3) perspective. 
 
 After having used all the pictures of the last figure, 
 now show your partner the next figure, which looks like 
 two solar systems. Ask him the following question: 
 ' ' If you were asked to cut out with a pair of scissors the 
 centers of the two solar systems pictured here (that is, 
 the two suns) in order to use these two suns as pictures 
 for the decoration of the walls of your room, and if you 
 had been asked to match these two pictures of only the 
 central suns as well as possible, which of the two con- 
 
50 
 
 PSYCHOLOGY DEMONSTRATIONS 
 
 centric circles seen in the right system would you prefer 
 as a match for that cut out from the left system?" . 
 Your partner's answer is undoubtedly the result either 
 of his reflexes or of his habits. "Was his answer deter- 
 mined by the first or the second or both of these two 
 habits enumerated below? 
 
 O O 
 
 oQo 
 
 O O 
 
 (1) Substituting for the phrase "this is small and 
 that is still smaller" the new phrase "that thing might 
 be too small to be a match." Do you think he has this 
 habit ? You might find out by skilful questioning wheth- 
 er such substitutions exist in his nervous system. Try 
 to find out. Skilful questioning for the purpose of dis- 
 covering what a person's hidden habits are, is nowa- 
 days, by many who use it professionally, called tech- 
 nically " psychanalysis. " You caji psychanalyze your 
 partner, if yoii just try hard enough. The fact that 
 many of your partner's habits are Mdden from you 
 (maybe hidden from him, too), does not indicate that 
 they are weak habits. However, you may perhaps feel 
 
WASTED HABITS OF ESTIMATING SPACE 
 
 51 
 
 confident as to -whether he has this habit or not, without 
 even psychanalyzing him. 
 
 (2) Substituting for the nomenclature "large system 
 — small system" the nomenclature "near system — far 
 system" (compare in your text on page 241 what is 
 said of figure A) and then again substituting for this 
 latter reaction the pronunciation of "small and large 
 sun." Has this last habit been discussed or hinted at 
 in any previous demonstration in this manual? Do you 
 think your partner has this habit? 
 
 "What then is your final answer to the question : "Was 
 your partner's choice determined by the habit (1) or 
 by the habit (2) or by both? 
 
 In the case (2) just referred to, was there again 
 ' ' perspective " ? If so, answer the question : "What thing 
 was here the start and what thing was the end of the 
 movement of looking thru? 
 
 Now turn to the third of the figures of this demon- 
 stration and show your partner the three pictures of 
 which it consists. In one of them he sees on one side a 
 
 
 
 
 
 ( ) 
 
 
 L — J 
 
 
 
 
 
 
 
 
 
 
 H 
 
 
 
 figure which looks like the cross-section of an old- 
 fashioned iron kettle, on the other side something re- 
 
52 PSYCIIOLOG'X DEMONSTRATIONS 
 
 sembling a palisade. Ask your partner whether he 
 thinks that after cutting out with a pair of scissors the 
 exact kettle he could or could not cover the palisade. 
 Would a piece of the latter picture remain uncovered 
 by the kettle? Or, if he tried to cover the kettle, would 
 a piece of it remain uncovered by the picture of the 
 palisade ? 
 
 Ask him the same questions with respect to the pic- 
 ture of which one side looks somewhat like the cross- 
 section of a thick cushion and the other side like steps 
 leading up to a building. 
 
 Ask him again the same questions with respect to 
 the third picture of the figure, where you have on both 
 sides something looking like a fence and between the 
 two fences a piece of unfenced "landscape." A.sk him 
 in this case whetlier he thinks that by cutting out the 
 horizontal strip of one of the fence pictures he could or 
 could not exactly cover, or would cover more than, that 
 strip between them picturing a "vacant landscape." 
 
 Has ' ' perspective ' ' anything to do with these ' ' wasted 
 reactions"? (By the way, what reactions of your part- 
 ner are here wasted?) Does your partner look "thru" 
 that cushion? Does your partner look "thru" that 
 flight of stairs? Does your partner look "thru" that 
 kettle? Does he look "thru" tliat palisade? Does he 
 look "thru" that piece of fence? Does he look "thru" 
 that vacant landscape ? In every case in which he really 
 looks "thru" something definite, he must tell you what 
 the start and the goal were between wliich the "thru" 
 movement occurred. Perhaps there was less looking 
 "thru" in some of these pictured things than in others. 
 Does that make your partner's illusions plausible? 
 
WASTED HABITS OP ESTIMATING SPACE 53 
 
 (Remember that looking "thru" means favoritism to 
 some point in a certaii' eye-adjustment. Coitipare p. 49.) 
 
 A very different way of explaining these illusions is 
 the old-fashioned one of some who have said that the 
 six kinds of things shown in the last figure should be 
 put in two classes: (1) Areas which show subdivisions 
 and (2) areas which show no subdivisions. They have 
 further said that it is worth while to remember the 
 "law" that a subdivided area always looks longer than 
 one that is not subdivided. 
 
 Let us warn you against that "law". It is not worthy 
 of such a name. Trying to apply that specious law you 
 might ask your tailor to subdivide your suit lengthwise 
 by designing it with many lines running across it, hori- 
 zontally, as in that flight of stairs. If you hoped that 
 that would make you appear taller to other people, you 
 would be disappointed. Why? Because the length of 
 your body does not offer to the spectator any "perspec- 
 tive," and nothing depending on "perspective" could 
 thus become actual in the habit functions of your friends 
 looking you over. 
 
 On the contrary, your friends, instead of calling you 
 tall, might call you stout because the horizontal lines 
 would be likely to induce them to give your width that 
 very measurement which you are not anxious to have 
 applied to you, which indeed you are avoiding. As in 
 vesture so in architecture subdivisions made by long 
 lines do not call forth any exaggerated judgments of 
 the space crosswise to these lines, but rather of the space 
 along the lines. In Gothic architecture, for example, the 
 prevalence of the vertical lines is intended to — and does 
 — impress the spectator with the direction leading to 
 
54 FHYCHOLOGY DEMONSTRATIONS 
 
 , heaven. And in classic architecture the long horizontal 
 lines tend to call forth the judgment of "broad" and 
 firmly resting on the earth rather than that of "tall". 
 Beware, therefore, of applications of this specious law 
 to dressmaking or to architecture. 
 
 XII. Xatural and Artificial Blind-Spots. 
 
 Anatomy tells you that the spot on the nasal side of 
 your partner's retina where the optical nerve enters 
 is not supplied with sensory cells. Use the index of 
 your text and find out what your text tells you about 
 the possibility of reacting by means of the localizing re- 
 fiex to a stimulating object which sends its light rays 
 exactly to that spot. 
 
 How would you proceed in order to demonstrate the 
 blind spot in your partner's eye? You might take an 
 old newspaper and paste somewhere on the printed mat- 
 ter a round bit of white paper of about one inch di- 
 ameter. Then make a conspicuous fixation mark (a 
 cross made with a black or colored pencil, for example) 
 about five inches to one side of that piece of white 
 paper. You may ask the instructor for some cards 
 already prepared in the manner just mentioned. 
 
 Are you going to permit your partner to keep both 
 eyes open? If not, why not? If you are going to use 
 his right eye on the fixation mark, should the white 
 paper be pasted on the right or on the left side from 
 the fixation mark ? In order to answer the last question 
 correctly, recall that the optic nerve does not enter the 
 eyeball in its "pole" (where the fovea of the retina is 
 located), but a little toward the nose in either eye. 
 
XAf URAL AND ARTIFICIAL BLIND-SPOTS 55 
 
 Now make your partner keep his eye steadily on the 
 fixation mark while he moves that newspaper or pre- 
 pared card toward and away from his face until he has 
 found th.€ distance at which he can truthfully exclaim 
 that the white paper pasted on the figured background 
 has entirely disappeared. Prom that moment on he 
 must keep eye and newspaper or card perfectly still in 
 order to answer your question whether be is willing to 
 say that instead of the white paper there is now a hole 
 in the figured background or what else he is willing to 
 call it. Most likely what he now tells you about that 
 spot itself will, in no way differ from what he tells you 
 about the surroundings of the spot. Try a checker 
 board and other figures on your partner for the same 
 purpose. 
 
 There are, liiowever, exceptions to what was said at 
 the end of the last paragraph. Eor example, if you use 
 two circles slightly overlapping, and have just the over- 
 lapping parts extinguished by the blind-spot, it is doubt- 
 ful whether your partner will describe the whole thing 
 as two complete circles. Try him out. If he, on request 
 to indicate what there is before him, draws two incom- 
 plete circles, there is only one explanation of this. It 
 must be a stronger habit. He must be more familiaT 
 with things resembling two incomplete circles than with 
 "two rings slightly overlapping". Try to psychanalyze 
 him and thus to discover what his hidden habits are. 
 Try to find out whether he handles, this or that or an- 
 other kind of things more frequently. Suggest to him, 
 in addition to pairs of things, such thiiigs as link sau- 
 sages, bales of cotton or hay, parcels or sacks stuffed 
 with soft material and tied tigliitly with a string, and 
 
56 I'SYCIIOLOGY DEMONSTRATIONS 
 
 SO forth. .Maybe you will discover why this t-nse with 
 the blind-spot was seemingly an exceptional one and 
 after all is not exceptional. 
 
 Now you can tiy out your partner's habits of using, 
 instead of his natural, an artificial blind-spot. An ar- 
 tificial blind-spot can easily be produced; it does not 
 require any drug application or surgical operation. Just 
 tell your partner to hold orfe of his fingers horizontally 
 before one of his eyes about six inches from his face, 
 while he closes the other eye. Make him look thru the 
 window at the sky ; or make him look at a large ground 
 glass window pane. After a little while ask him if his 
 'finger is not beginning to appear as if it wanted to 
 become transparent. But be sure to warn him against 
 becoming too interested in his finger ; he must be much 
 more interested in the sky or the ground glass than in 
 that finger, if he answers your last question in the 
 affirmative, tell him to hold a pencil at almost arm's 
 length so that it crosses the finger and ask him if he 
 can see the pencil thru the finger. You will get a very 
 surprizing answer. However, if you think it over, you 
 will recognize that the finger created "an artificial 
 blind-spot". And your partner's answer was depend- 
 ent on his habits. Give an example of such a habit 
 chosen from those which you observed with the natural 
 blind-spot. 
 
 However, without knowing what you -were doing, you 
 have actually done something to your partner that you 
 should never do in psychology demonstrations. You 
 have played a trick on him. You did it in the follow- 
 ing manner. 
 
 When you told your partner to close one eye, he 
 
NATURAL AND ARTIFICIAL BLIND-SPOTS 57 
 
 probably closed the lid with his lid muscles. Now, it 
 is virtually impossible thus to close one eye entirely 
 without closing the other eye at least partially. In all 
 probability your partner closed the upper lid of the 
 open eye so much that it obstructed considerably the 
 pupil, that is, the optical opening of the eyeball. And 
 even the lower lid probably obstructed the pupil. This 
 obstruction has an optical effect which physicists 
 call "dispersion" of the light. For simplicity's sake 
 let us in the following speak of black (which is really 
 lack of light) as if it were a special kind of light. In 
 all the reasoning that concerns us here it amounts to 
 the same. 
 
 Since the dispersion occurs mainly on the edge of 
 the upper lid, much light is thrown from the bright 
 background above over the dark finger region. And 
 some (more or less) light is also tlirown from the bright 
 background below over the dark finger region. Ask 
 your partner if he does not observe that quite clearly 
 as soon as he. brings his eyelids a little more closely 
 together. But when he holds his pencil verticaJhj (cross- 
 ing the horizontal finger) behind the finger, instead of 
 light "the black", a dark streak, from the upper piece 
 and the lower piece of the pencil is now thrown across 
 the broken space between the two pencil parts. And it 
 •is then, no matter what your partner's habits, unavoid- 
 able that he should tell you that he sees the dark pencil 
 unbroken "thru" the much lighter, translucent, so to 
 speak, finger region. He simply sees there the disper- 
 sion of the black appearing pencil. 
 
 You can make tlue existence of the fact just mentioned 
 — this trick played on your partner — still more obvious 
 
58 PSYCHOLOGY DEMONSTRATIONS 
 
 by asking him to slant the pencil 20 or 30 degrees. At 
 once your partner will tell you that that pencil piece 
 which is seen "thru" the finger has broken into two 
 parts, both being, not slanting, as the pencil, but ver- 
 tical, the upper one failing from the place where the 
 upper pencil touches the finger region, the lower one 
 rising from the place where the lower pencil touches the 
 finger region. And the falling one of these tM'o vertical 
 streaks is probably more conspicuous because the dis- 
 persion of the black appearing pencil is probably more 
 powerful on the edge of the upper, more obstructing, 
 lid than on the edge of the lower lid. 
 
 In order to avoid this trick you have to insist that 
 your partner keep his seeing eye wide open, the lids as 
 widely separated as possible. Obstruct, then, the not 
 seeing eye, whose lids will also be widely separated, by 
 tying a thick black cloth loosely over it. Now let him 
 put his finger again before the seeing eye, against the 
 same bright background. Let him hold his finger in 
 any position, perhaps, for a change, in a vertical posi- 
 tion. Let him look steadily until, again, tlie finger 
 begins to become translucent, as it were. This will 
 not occur so readily when you do not use that trick, and 
 you must have more patience with your partner now 
 than before. But when it occurs, let him again place 
 his jteiK-il across at the same distance behind the finger, 
 move it slowly up and down, change the angle of slant, 
 remove the pencil altogether, replace it again, and so 
 forth, but holding his finger and his eye as still as pos- 
 sible during all this time. 
 
 Notice if your partner's actions, describing what he 
 sees, do not reveal habits quite similar to those which 
 
NATURAL AND ARTIFICIAL BLIND-SPOTS 59 
 
 function with the blind-spot. If that is so, you are 
 entitled to speak of an artificially created blind-spot in 
 this case. 
 
 Try now still another method. Take a red disk of 
 about three inches diameter, put it on a white disk of 
 about five inches diameter, (the actual dimensions mat- 
 ter little) and spin the set on the color wheel. Tell 
 your partner to look at the color wheel 'steadily, best 
 keeping his eye fixed on the center. After a minute or 
 more ask him if the whole disk does not look as if a 
 veil, partly more, partly less dense, had been drawn 
 over it; and if the white ring, more particularly, does 
 not appear as if it were a tfanslucent veil thru which 
 a colored background could be noticed. "Without spin- 
 ning the double disk he would probably deny it because 
 his liabits are not such that he would very readily apply 
 to a white paper disk like the one employed the name of 
 a veil, cloud, or something similarly translucent, while 
 the disk was standing still and this or that dot, dent, 
 or other special feature of it could be clearly noticed. 
 But when the disk is spinning you may find him willing 
 to do that. 
 
 Ask your partner of what color the background is 
 which seems to shine thru the "veil". How do you 
 explain his answer? What must be his habits? How 
 is this case related to the preceding two cases ? That is, 
 if you speak, here too, of an artificially created "blind- 
 spot", what is the shape of this artificial blind-spot in 
 comparison with the shape of the other blind-spots? 
 
 Popular language in all these eases of blind-spots 
 would say that the blind-spot "is filled in by the imagi- 
 nation". Compare, by utilizing the index, what you 
 
60 PSYCHOLOGY DEMONSTRATIONS 
 
 fi)id about imagination in your text. More exact — 
 scientific — language says in the case of a blind-spot 
 merely that when your partner's action was observed 
 by you, "not everything" which seemed to be reacted 
 to, "really existed" or "need really have existed" as a 
 stimulus. Thus you may say that you have here ex- 
 amples of actions more complex than the stimulation 
 seemed to warrant. Has this last statement any logical 
 relation to the explajnation of Aristotle's illusion given 
 on page 227 of your text? Does the case of reacting to 
 a blind-spot perhaps reciuire for its complete explana- 
 tion the application of both the principles of figure A 
 and figure B on page 224 of your text? 
 
 XIII. Binocular Rivalry and Co-operation. 
 
 Read pages 245 to 255 of your text. Ask the instruc- 
 tor to give you a collection of cards suitable to test your 
 partner's actions in ease a different picture is presented 
 to a corresponding region of his right and his left eye. 
 The question in these eases is not simply ' ' One or two ? ' ' 
 It is to be taken for granted that your partner will 
 always answer "One". Ask the instructor for a stereo- 
 scope so that you may easily present the picture on the 
 right side to your partner's right eye and the picture 
 on the left side of each card to your partner's left eye 
 in such a manner that he will always look at the center 
 of each picture and will always be inclined to say ' ' One ' ', 
 in so far as this can be controlled by merely regulating 
 the direction from which either stimulation proceeds 
 toward the eye. 
 
 But how can he, the organism, call out "One" when 
 one of the two organs in service at the time orders him, 
 
BINOCULAR RIVALRY AND CO-OPEKATION 61 
 
 the organism, to call "the thing" by one name and the 
 other organ orders the same organism to call "it" l)y a 
 contradictory name!' You will notice that the organism 
 escapes from this dilemma in one of three ways. Some- 
 times by the two organs (1) compromising and thus in a 
 way co-operating. Sometimes by the two organs (2) 
 dividing the labor, avoiding mutually an encroachment 
 upon each other's division of the task, and thus in a 
 manner co-operating. But sometimes the organs com- 
 pete so fiercely that nothing is left to the organism to 
 do but to carry out (3) either all the time only the order 
 of the one or only of the other, or to carry out alternately 
 the order of the one for a little while only, then that of 
 the other for a little while only, again of the one, again 
 of the other, and so forth. There is, of course, nothing 
 absolutely contradictory in such an alternation. Do 
 we not, free from contradiction, call, for example, the 
 same field on a farm on alternate occasions a wheat field, 
 a stubble field, a wheat field again, a stubble field again, 
 and so forth? 
 
 In your partner 's reactions to the cards of which your 
 instructor gave you a set find examples (1) of the first 
 kind of nominal co-operation above mentioned of the 
 sense organs, (2) of the second kind of nominal co- 
 operation of the sense organs, and (3) of the obvious 
 competition of the sense organs. Of course, triie co- 
 operation between the two sense organs is such an or- 
 dinary fact in human life that you would not have to 
 spend time in the laboratory in order to demonstrate it. 
 Find these examples by showing to your partner the 
 cards in the order mentioned here below. 
 
 Begin with the card which is pink on one side and 
 
62 PSYCHOLOGY DEMONSTEATIONS 
 
 light green on the other. Place it in the stereoscope 
 and let your partner adjust the stereoscope to suit him- 
 self. Give him ample time to look. Ask him if he ever 
 calls the whole thing or any whole and uniform part of 
 the thing "a pinkish green or a greenish pink". Ask 
 him if he ever happens to be inclined to say that a veil 
 is being thrown over the thing or that colored clouds 
 appear on it. Ask him again and again how he would 
 describe it now, and how he would describe it now, and 
 how now, and how now. 
 
 Now be sure to read to your partner page 99, be- 
 ginning with the last para^aph, and all of page 100 of 
 your text. Then discuss with your -partner whether his 
 actions are more likely to be due to the law of the re- 
 sultant or to the law of the competition of nervous 
 currents. Was there anything in your partner's action 
 that could be called a compromise? Was there anything 
 in your partner's action that could be called a consistent 
 and fruitful division of labor between the two sense or- 
 gans? Was there anything that could be called fierce 
 and never really ending competition? Which of the 
 three ways of escaping from the dilemma (look three 
 paragraphs back) is illustrated by this card? 
 
 In the same way now try on your partner the card 
 of which one side is dark yellow and the other side blue. 
 Ask and discuss the same questions. 
 
 Try now card 25 of "Titchener's Series". Is there 
 anything in your partner's action which you would call 
 fierce and never really ending competition? Or is there 
 evidence that at least one of the eyes divides the labor 
 so that it (I) leaves a certain task wholly to the other 
 eye and (II) truly co-operates with tlie other eye in 
 
BINOCULAR RIVALRY AND CO-OPERATION 63 
 
 everything else? Which of these two cases, I and II, 
 would then be represented by which of the three figures 
 on page 224 of your text ? And which of the two eases, 
 I and II, would be represented by the figure on page 105 
 of your text? 
 
 Try now card 26 of "Titchener's Series" on your 
 partner. Is this case like that of card 25? Or almost 
 like it? Or entirely different from it? If entirely 
 different, what is the difference? If almost like it, what 
 is the only difference ? 
 
 Try card 27 of the same series. Answer the same 
 questions. What are the best conventional (tliat is, 
 agreeing A\ith universal customs and not only with your 
 partner 'tr individual language customs) names which 
 the two-eyed organism could pronounce for the whole 
 thing regarded as something real, in the several cases 
 of tlie cards 25, 26, and 27? Would "monogram" be a 
 good name in one or more of the three cases? 
 
 Next try on your • partner the card which is an en- 
 largement of the figure on page 253 of your text. It is 
 number 28 in "Titchener's Series". Read what you 
 find on page 253 and 254. Do you find with this card 
 any tnit co-operation between the two sense organs? 
 Do you find any competition that is of the kind of 
 nominal co-operation which may be called division of 
 labor? Do you find any nominal co-operation of the 
 nature of a compromise? What conventional name for 
 the thing (or that part of the thing which is in question) 
 does your partner propose in case you have an affirmative 
 answer to the last of the preceding questions? What is 
 gloss (or luster) ? What adjective with three hyphens 
 is used on page 254 of your text instead of "glossy"? 
 
64 PSYCHOLOGY DEMONSTEATIONS 
 
 Would there be gloss in this world if "time" did not 
 exist? What becomes of gloss when you photograph it? 
 Did you ever see a photograph of the gloss of a person's 
 spectacles ? Do you still call it gloss in the photograph ? 
 
 Try cards 29, 30 and 31. Does co-operation seem to 
 weaken and competition seem to become fiercer as your 
 partner passes from card to card? What must be the 
 conditions of the streaming of excitation thru tlie nerv- 
 ous system which make deflection as described on page 
 105 of your text so rare a possibility with card 27 as 
 compared with its probability in cards 29, 30, and es- 
 pecially 31 ? Can previous habit formation (resistance 
 reduction as in the figure on page 124 of your text) 
 have anything to do with these conditions? 
 
 Now give your partner card 32 to look at. Tell him 
 that the apparent and maybe surprizing "solidity" of 
 the crystal is at the present moment a mere by-product 
 Avhich he may overlook since he will have a chance later 
 in the course to demonstrate similar solidities on you, 
 as you will then on him. Ask your partner which of 
 the questions answered in the affirmative when he looked 
 at card 28 have an application here, both with regard 
 to the crystal and with regard to the background. 
 
 Give your partner cards 33 and 34 to look at and — as 
 some people say — "psychanalyze" him, that is, listen to 
 him carefully while he is talking himself out. Is there 
 anything in his actions while looking at card 33 which 
 you would call a demonstration of true co-operation of 
 his two sense organs? Is there at times a nominal co- 
 operation of the kind of a compromise? Is there at 
 times one of the kind of division of labor? Is there at 
 times any fierce competition resulting in the organism 
 
BINOCULAR RIVALRY AND CO-OPERATION 65 
 
 alternately obeying the orders of the one only and then 
 only of the other sense organ? If you answer any of 
 these questions in the affirmative, write down exactly 
 what part of the field of vision your answer refers to. 
 Answer the same questions with respect to card 34. 
 
 Now use card 35 on your partner. We shall use this 
 opportunity for discovering whether you are a good psy- 
 chanalyst, that is, whether you have skill in guessing 
 3'our partner's hidden habits about whose formation you 
 have no testimony of witnesses. Does your partner's 
 action make it probable that sometime in his life he 
 acquired the liabit of calling a real thing of a certain 
 description by a certain ncmte'l Of what objective de- 
 scription, used by witnesses in court, say? Perhaps: 
 being oval, with four legs, being blue, and now and 
 then turning red? Or what other description? And 
 by what name? Perhaps: a coffin? Or a rabbit? Or 
 what other name ? As soon as you guess what the hidden 
 habit is, his prevailing reaction to card 35 will become 
 quite plausible to you. When you have found the right 
 name, pick out from our discussion of card 28 the ad- 
 jective which is virtually, in some situation of life, the 
 synonym of that noun. (Did your partner ever stand 
 on the outside of a house looking at its parts?) 
 
 Now give your partner card 36. Do your partner's 
 actions reveal any true co-operation of his two sense 
 organs?, and where in the field of A^sion? Or any di- 
 vision of labor ?, and where in the field of vision ? 
 
 Card 37 will remind you of card 32 in thds respect, 
 that you may again believe it to be intended for the 
 demonstration of an apparent "solidity". However, 
 while the card might be used for that, that is by no 
 
66 PSYCHOLOGY DEMONSTRATIONS 
 
 means the intention here. Ask your partner if he dis- 
 covers any gloss, any luster. If he does, discover the 
 objective cause of it. You can discover that, if you 
 utilize what you learned on card 28. What you had 
 there in a big' bulk, you have here in many little details. 
 But it requires a ver.y minute inspection and com- 
 parison, a regular survey of the two pictures on card 
 37 in order to discover a few of these details. You will 
 not find them either in the boat or in the shrubs on 
 shore. But where most likely? ("Where in the land- 
 scape would you expect gloss?) 
 
 Take now card 40, which is described on page 255 
 of your text. Read that page. Remember how your 
 partner acted with the first two cards, when you put 
 red before one of his eyes and green before the other, 
 or when you put blue before one and yellow before the 
 other. Do you conclude from your partner's actions 
 that the competition between the nervous currents com- 
 ing from the two eyes is equally fierce now when you 
 put blue before the one eye and green before the other, 
 or blue before the one eye and red before the other ? Or 
 is there a greater tendency toward a nominal co-operation 
 in the two cases of card 40 ? 
 
 "Would you accept the following threefold statement 
 about the behavior of the nervous currents toward each 
 other as an interpretation of your partner's actions? 
 
 "With antagonistic colors: — competition most fierce, 
 
 "With dissimilar colors : — competition much less fierce. 
 
 With somewhat similar colors: — competition still less. 
 
 Look up on page 283 of your text, in the lower para- 
 graph, what colors are antagonistic. Do not fail to 
 compare the figure mentioned there. 
 
BINOCX'LAR RIVALRY AND CO-OPERATION 67 
 
 Look up on page 270, in the paragraph beginning on 
 that page and ending on the next, what is meant by 
 colors being "somewhat similar". 
 
 Now give your partner card 38, which is really only 
 a double frame. By placing in the two windows of the 
 frame bits of colored or uncolored and brighter or dark- 
 er paper, you can try out any combination of excita- 
 tions of the two eyes that you may be interested in. 
 
 Card 39 you can probably use most advantageously 
 by instructing your partner to adjust the stereoscope 
 so that the two inner (one blue, one red) squares co- 
 incide within what he will call "the real thing"; and 
 that the two outer squares (one blue, one red) remain 
 separate and upon the outskirts of that thing: Give your 
 partner ample time to watch, and listen patiently to his 
 description. What former experiences are here ex- 
 hibited again? 
 
 Card 41 may caU. forth in your partner the applica- 
 tion of the name "green" to a certain part of the field 
 of vision, and you may have ready at once, as ' ' explana- 
 tion", the fact that painters often mix green paint out 
 of blue and yellow pigments. Disillusion yourself. You 
 will learn on page 273 of your text that the explanation 
 is not so simple: Cut two holes in a white piece of paper, 
 and cover thus all the red parts of the card, and let your 
 partner look again. You will discover, unless your pa^ 
 per is translucent, that the red is the chief if not the 
 only cause of the "green" being spoken of by your 
 partner. 
 
 Card 42 will again exhibit some former experiences in 
 a new variation. 
 
68 PSYCHOLOGY DEMONSTRATIONS 
 
 XIV. Stereoscapy and Pseudoscopy. 
 Stereoscopy 
 
 Take a hollow truncated cone, made of paper or tin, 
 and place it before jour partner so that he can see the 
 outside (that is, with the smaller of the two circular 
 openings nearer to him than the larger opening). It 
 is not necessary that the axis of the cone fall in the 
 median plane. Indeed it is preferable to have the axis 
 cross your partner's median plane under a small angle, 
 say, one of ten degrees. See that your partner keeps his 
 bead as still as possible, while you make him close the 
 left eye and draw with the pencil the two circles as they 
 appear to his right eye in relative position, and then 
 close this eye and, without having made any head move- 
 ment, draw the two circles on the left of the drawing 
 just made as they now appear to his left eye. Call this 
 double picture for convenience's sake I. 
 
 Then turn the truncated cone around so that your 
 partner can see its inside and make him draw again a 
 double picture under the same conditions as before. Call 
 this double picture II. Now ask the instructor to give 
 you the cards of "Titchener's Series" from 1 to 24. 
 Pick out from this series card 7 and see whether this 
 agrees in its essential features with your partner's draw- 
 ing I or with his drawing II. You can thus tell whether 
 the person who drew the card 7 had the smaller opening 
 of the hollow cone closer to himself or farther away from 
 himself than he had the larger opening of the cone. 
 
 Now read what you find about stereoscopic vision on 
 pages 256 to 260 of your text. Memorize the two rules 
 which you find on page 258 in the lower paragraph be- 
 
STEEEOSCOPY 69 
 
 ginning M'ith the word "Experience" and in the para- 
 graph beginning below tliis and ending on page 259. 
 "Without knowing these two rules by heart your chance 
 of understanding stereoscopy and pseudoscopy is prac- 
 tically zero. 
 
 Now let j'our partner place card 7 in the stereoscope 
 which you get from your instructor. Let your partner 
 properly adjust the instrument. Notice if he more fre- 
 quently (if he speaks of "nearer" and "farther" at 
 all) calls the smaller circle nearer or the larger circle 
 nearer. (Of course, th«re is no law of nature nor any 
 statute law which could prevent him from doing either.) 
 Is the greater frequency of one kind among his reactions 
 in accordance with the supposedly existing habit which 
 you just memorized in those two rules? Or is it not in 
 accordance ? 
 
 Try now the cards 6 and 5 on your partner in the 
 same manner. What is the likeness and what the only 
 difference from number 7 of each of these cards? 
 
 Try now cards 4, 3, 2 and 1. Apply again the rules 
 which you memorized. Then let your partner use these 
 cards in the stereoscope. If you should find him less 
 determined in these (simpler) cases, can you state a 
 reason for that? Are the orders, so to speak, received 
 by the organism to do something definite with the things 
 shown on these four cards fewer than they are with 
 the cards o, 6 and 7, and do you regard this as a plausible 
 reason why the organism does this definite thing with 
 more vacillation? Do you "stick up your hands" with 
 less vacillation when one highwayman orders you to do 
 it or when several highwaymen give you the order? 
 
 Cards 8 and 9 do not introduce any new principle. 
 
70 PSYCHOLOGY DEMOXSTEATIONS 
 
 In card 8 tliere are two quite independent things to be 
 seen at the same time. And in card 9 there are even five 
 things, all independent, to be seen at the same time. All 
 one can say is that these cards approach more the con- 
 ditions of everyday life where, in seeing a furnished 
 room or a landscape, one sees many things at the same 
 moment. 
 
 About the same is to be said of cards 10, 11, 12, 13 
 and 14. The number of details seen at the^same moment 
 increases from case to case. 
 
 Now take the photograph, card 15. Try to. apply the 
 rules (which you memorized) by proceeding in your 
 reasoning in tlie opposite manner. Instead of picking 
 out two things or details which are quite obviously, one 
 picture in comparison with the other picture, displaced 
 relative to each other, pick out two things (without us- 
 ing the stereoscope at all) which are quite obiiovsly at 
 different distances from the photographer. Then meas- 
 ure their distance horizontally from, each other in each 
 picture. 
 
 With most things you select you will need a pair of 
 compasses, calipers, or a ruler to take that measurement. 
 But with a few wisely selected things you can measure 
 exactly enough with the naked eye, without any cali- 
 pers. To do that you must select two things which are 
 almost exactly in line from the photographer, for ex- 
 ample, the man and a point on the rail of the bridge just 
 barely not hidden by his body. 
 
 Card 16 is a very interesting pair of pictures of the 
 moon photographed from two laterally distant places 
 on earth ; but you will find it almost impossible to select 
 two things on its surface for the same comparison which 
 
STEREOSCOPY 71 
 
 you just made in the bridge pictures The photograph 
 17, on the other hand, is again very suitable for such a 
 comparison of two things with regard to their relative 
 displacement in the two pictures. 
 
 Cards 18, 19, 20 and 20-Bxtra will give food for re- 
 flection to those students who are fond of it. But they 
 will not elicit from your partner any very definite re- 
 action when he looks at them in the stereoscope. 
 
 Cards 21 and 24 sene the negative purpose of calling 
 attention to the fact that only lateral displacement of 
 one tiling relative to another (no vertical displacement) 
 plays a role in stereoscopy. If you were the Creator and 
 had made up your mind that in the race created by you 
 vertical displacement should be a factor in "depth per- 
 ception", how would you arrange your partner's eyes 
 or what new eyes would you give him ? 
 
 Cards 22 and 23 may elicit from your partner the 
 remark that lie is more ready to "imagine" (that is, to 
 call) the thing on card 22 "a slanting oval" and also 
 to "imagine" the things on card 23 "three (two round 
 and one square) wire hoops of equal size, but in perspec- 
 tive " if he closes one eye than if he keeps both eyes open, 
 in either case using the stereoscope. Why is your part- 
 ner more ready for perspective vision (for "looking 
 thru" the world) if he opens only one eye? In order to 
 give the right answer to this question, you must first 
 learn to give the right answer to the following question : 
 What is the difference in meaning between saying ' ' The 
 lateral displacement is now zero" and saying "There is 
 no lateral displacement existing"? 
 
 You actually will have, without needing for that any 
 stereoscope (why not?), the same case as that of card 22 
 
72 PSYCHOLOGY DEMONSTRATIONS 
 
 or 23 whenever you make your partner visit an exhibi- 
 tion of paintings. Imagine that you are the artist whose 
 paintings are on exhibition. It might be to your inter- 
 est, then, to advise your partner to close one eye. Why ? 
 "When he visits your exhibition, are you very anxious 
 to warn him against mistaking these wooden frames for 
 w^ndow frames of some sort? Are you very anxious to 
 keep him reminded that thiey serve to keep the pied 
 canvases stretched flat? Or would you rather have him 
 forget all about those canvases and call them vsrindow 
 panes ? " 
 
 There are some curious kinds of "stereoscopic views" 
 for sale in high class toy shops. With these kinds you 
 do not look thru a "stereoscope" at all. With one kind 
 you simply take the picture you have bought in your 
 hands and look at it (apart from observing a certain 
 rule about holding it) just as you would look at any 
 picture. This kind is called "parallax-stereograms". 
 With another kind you have to put on your nose a kind 
 of spectacles differently colored for each eye. But 
 again j'ou hold — at least it seems so at the first glance — 
 only one, and an apparently poorly printed, picture in 
 your hand. This kind goes under the commercial name 
 of "plastographieal views". Ask the instructor for 
 samples and explain how the stereoscopic effect is brought 
 about in these eases. 
 
 Before leaving stereoscopy, you might answer the fol- 
 lowing questions concerning the common stereoscope, 
 which are not strictly psychological questions, but whose 
 an.swers may aid you on various occasions in life. 
 
 1. Since it is difficult to diverge or even parallel 
 the eyes, why do the commercial makers of stereoscope 
 
STEREOSCOPY 73 
 
 cards insist on making the distamce of the pictures from 
 center to center greater than the interpupillary distance? 
 
 2. What is that shape of the glasses, put by the mak- 
 ers of stereoscopes into these instruments, which does 
 awaj^ with the difficulty spoken of in the previous ques- 
 tion? 
 
 3. The makers of stereoscopes make the prisms so 
 that the real axes of your eyes converge at a point a 
 goodly number of rods distant from you. Why do those 
 makers dislike to have your point of convergence nearer 1 
 (Remember what kind of thing is usually photographed 
 and viewed stereoscopically.) 
 
 4. Having your point of convergence at such a dis- 
 tance enforces an accommodation for the same distance, 
 that is, makes you far-sighted. How does the maker of 
 the stereoscope shape the prisms in order to overcome 
 that far-sightedness of its user? (Inform yourself as 
 to whether far-sighted people buy spectacles with convex 
 or with concave glasses.) 
 
 5. Why does not the. dealer in stereoscopes simply ex- 
 pect you to hold the photograph far enough from your 
 eyes to suit your far-sightedness? (Why do not far- 
 sighted people, when they want to read the newspaper, 
 simply hold it as far from their eyes as the natural 
 accommodation of their eyes calls for?) 
 
 Pseudoscopy 
 
 Pseudoscopy, as we use the term here, differs from 
 stereoscopy, not by any discrepancy of principles (you 
 use the same rules already memorized), but merelj' by 
 the fact that you make your partner look at a real thing 
 instead of at a double picture of a tiling. You may, 
 
74 PSYCHOLOGY DEMONSTRATIONS 
 
 when you read that sentence, think for a moment : "Well, 
 that is then, nothing but what I do everj^ moment of my 
 life, having always real things before my eyes." True, 
 — but for pseudoscopy it is necessary to have an optical 
 instrument which you do not have every moment of 
 your life. This instrument is generalizingly called a 
 "pseudoseope". The word "generalizingly" is em- 
 phasized in the last sentence because you cannot go 
 into a store nor even into a laboratory of physics and 
 ask for a pseudoseope. That would be like going into 
 a drugstore a)id asking for a "beautifier". There are 
 many very different optical instruments which can be 
 used to make a thing look " pseudoscopie ". You will 
 handle here only a few of the simplest ones. 
 
 Take first the so-called "total-reflection pseudoseope". 
 Do not permit yourself to be confused by the word 
 "total". That is a (physicist's) term which to you, 
 here, is entirely irrelevant and only serves to charac- 
 terize commercially the pieces of glass thru which you 
 have to look. If you want to buy these pieces of glass, 
 you have ta order them under the commercial name 
 of "total reflection prisms". 
 
 The best things ("real things") to use as objects to 
 look at thru a pseudoseope are such things that, and 
 placed in such situations that, neither the habits illus- 
 trated on page 241 nor the habits mentioned on page 244 
 of the text have a likely chance to function. In order 
 to subdue the former, it is especially advisable to use a 
 thing no part of which hides or shades any other part 
 of it, and which is known to exist in this world in re- 
 versible forms. A bouquet of flowers, for example, 
 would not serve at all, for some of its flowers are partly 
 
PSEUDOSCOPY 75 
 
 hidden by others. Neither would a sculptured bust serve, 
 for a human head appears always convex, never con- 
 cave, and is therefore not reversible. But the hollow 
 truncated cones, which we have already used, will serve 
 very well, provided they are not placed so that one part 
 hides another part, and provided the illumination is so 
 diffuse that no part appears conspicuously shaded. If 
 the illumination is troublesome, a model made of black 
 wire and placed before a white wall is preferable. — In 
 order to avoid the habits (p. 244) based on accommoda- 
 tion and convergence, it is advisable to avoid moving 
 the eyes, that is, to keep the gaze fixed on a definite 
 point while using the pseudoscope. 
 
 The simplest and best object to look at, however, con- 
 sists of three cardboard targets, about two inches square 
 (so far as they are visible), of different colors, so that 
 one may easily speak of each" under its color name, and 
 also of sufficiently different size to avoid the suggestion 
 that thej' are meant to be alike. Place these targets on 
 a little table (say, fifteen inches square) which stands 
 about five feet above the floor and which bears on its 
 front a strip of wood or cardboard high enough to make 
 it impossible to see the table surface on which the tar- 
 gets stand. Place the three targets in echelon so that 
 none of them hides any part of any other, and one of 
 them about four inches, one about eight inches, and one 
 about twelve inches from the front of the table. 
 
 Give \oxiT partner the orders and questions of the 
 following paragraph. These are not psychological ques- 
 tions at all, but are intended only to make him familiar 
 with the instrument and to get the instrument adjusted : 
 
76 PSYCHOLOGY DEMONSTRATIQNS 
 
 " (1) 7/ the distance between tlie prism tubes from 
 center to center differs gredtly from your interpupillary 
 distance, move that prism tube which is fastened in a 
 slot after you have loosened the bottom screw. But this 
 adjustment is probably already made when you receive 
 the instrument. Therefore, do not play with it. (2) 
 Understand that the small round openings of the instru- 
 ment are meant to be placed next to your eyes. (3) 
 Look at the instrument from above and make sure that 
 the prism tubes are approximately parallel. The screw 
 on the right will set them parallel without any risk. 
 (4) Look now with one eye only (closing the other eye) 
 and convince yourself that by turning the prism tube 
 within the larger tube holding it you can tilt the target 
 table. (5) How many degrees do you have to turn the 
 prism until the table appears upside down? (6) How 
 much more do you have to turn in the same direction 
 in order to make the table appear upright again? (7) 
 Close the one and the other eye alternately and make 
 sure that the prisms make the table appear exactly up- 
 right to either eye. (8) Look at a small object (a pic- 
 ture or a light fixture) on the wall ten or more feet 
 away. With hoth eyes open turn the screw on the right 
 until you see that small object clearly double; then 
 turn the screw back until both those identical objects 
 exactly coincide and leave the screw from, now on alone. 
 You and the instrument are now ready for our psy- 
 chological demonstration." 
 
 After having done all this to your partner, tell him 
 to stand five or ten or more feet from the target table 
 and to look thru the pseudoscope at the table. In all 
 pseudoscopy demonstrations, if your partner ordinarily 
 
PSEUDOSCOPY 77 
 
 wears glasses, make him wear his glasses. Tell him to 
 keep his eyes on one of the targets (remember page 244) 
 no matter what questions you ask him about the others. 
 What are the reasons for keeping the gaze constant in 
 every pseudoscopy demonstration? Ask your partner, 
 now, which of the targets, using their color names, he 
 would call the nearest and which the farthest. Write 
 down his answer. 
 
 Tell your partner, then, to look at a person's profile 
 alternately with the naked eye and thru the prisms and 
 to tell you wJiat such a prism really does to the image. 
 Now look at page 258 of your text. Suppose that you 
 had made the two drawings I and II looking with the 
 naked eye, and that you had then made the drawings 
 III and ly after looking at your finger and pencil thru 
 such a prism. What would III and. IV then appear like ? 
 Redraw in your note book III and IV in accordance with 
 your partner's answer to the question what such a prism 
 really does to the image {profile). 
 
 Is it clear, then, that your partner could not help (if 
 his targets were a finger and a pencil) saying ahoitt the 
 distance of the fing'er exactly that which normally he 
 ivould say about the distance of the pencil? 
 
 Human beings have this advantage over animals that 
 they can "generalize" (some call it; "reason"). Before 
 you continue reading this manual, look up the page 
 headings of pages 365 and 369 of your text. Let us 
 see now how well you can "handle words". Let us see 
 if, instead of making a concrete demonstration by put- 
 ting the above question to your partner ("which of 
 the colored targets, seen thru the pseudoscope, he would 
 call the nearest and which the farthest") you could 
 
78 PSYCHOLOGY DEMONSTRATIONS 
 
 have derived his answer by merely handling words (by 
 "reasoning"). 
 
 Take the two paragraphs, the one beginning with 
 ' ' Experience ' ' on page 258 and the one ending with ' ' vi- 
 sion" on page 259. Count how many times the words 
 "right" and "left" appear in each paragraph in each 
 of two significant connections. 
 
 Notice that these words) appear in two different con- 
 nections, sometimes in connection with "eye", some- 
 times in connection with ' ' to the ' ', meaning in the latter 
 case lateral direction. Now, did you ever take your 
 partner's eye out of the socket and put it in the other 
 socket? Not at all. Therefore do not do anything to 
 the words "right" and "left" in the two paragraphs 
 whenever they appear connected with ' ' eye ' '. But when 
 they appear connected with "to the" you 'should ex- 
 change "right" and "left", if your partner uses an 
 instrument that ' ' changes the profile ' '. 
 
 Now make your partner handle the words "right" 
 and "left", exactly as prescribed, in the first paragraph 
 after the words "might be called". That is, make him 
 rewrite that passage which is in quotation marks in his 
 note book in its new formulation. Compare the result 
 with what the unaltered second paragraph states. Do 
 you see now the agreement between your former con- 
 crete demonstration of your partner's actions and his 
 present abstract reasoning {handling of tvords) ? 
 
 Your partner's abstract reasoning, quite aside from 
 its value as exemplifying the discussion of chapter XVI 
 of your text (by the way, what is the title of that 
 chapter?), has a direct value for you in suggesting an- 
 other kind of concrete demonstration of pseudoseopy by 
 
PSEUDOSCOPY 79 
 
 means of another instrument to be put before his eyes. 
 Make your partner, for a change, rewrite again that 
 same passage of the first paragraph in question. But 
 make him rewrite it this time by doing nothing with 
 the words "right" and "left" when they appear con- 
 nected with "to the", but by exchanging "right" and 
 "left" whenever they appear connnected with "eye". 
 Compare the result with what the unaltered second 
 paragraph states. Do you expect from this mere reason- 
 ing (handling of words) that you will again succeed in 
 a concrete demonstration of pseudoscopy by means of 
 a new method? 
 
 For this demonstration, then, it is necessary to remove 
 at least one of the eyes from its socket. Let us, without 
 hreaking any of the nervous connections, remove your 
 partner's left eye and put it several inches to the right 
 of his right eye, so that his so-called right eye will func- 
 tion as a left eye (that is, on the other eye's left side) 
 and his so-called left eye will function as a right eye 
 (that is, on the other eye's right side). 
 
 We shall not, of course, perform this operation by 
 means of the' surgeon's knife, but simply by placing 
 before your partner's left eye a little mirror which 
 breaks the line of sight rectangularly and throws it to 
 the right, and by placing a second, preferably larger 
 mirror, on the right side of his head, but a little in 
 front, in order to break the line of sight again. "What 
 he really sees of our target table with his so-called left 
 eye is then that aspect which can be seen from the 
 position of the larger mirror, that is, from a position 
 on the right of his so-called right eye. The so-called 
 right eye then functions as a lefl^ eye in the stereoscopic 
 sense. 
 
80 PSYCHOLOGY DEMONSTRATIONS 
 
 Tell your partner to place his head so that his left 
 eye has the little mirror in front obstructing the view, 
 and sol that at the same time the right eye sees the target 
 table freely. Tell him, then, without changing the posi- 
 tion of his head, to take hold of the larger mirror and 
 swing it around its pivot until the target table appears 
 clearly double, and to swing it back until the target 
 table appears single. Your partner and the instrument 
 are now ready for the psychological demonstration, the 
 demonstration of his habits. Ask your partner which of 
 the targets, tising their color names, he would call the 
 nearest and which the farthest. — The "reason" for his 
 answer you have known already for some time, even 
 before asking the question. That "'reason" was your 
 very inducement for constructing this second kind of 
 pseudoscopic instrument. Let us call this instrument an 
 "eye transplanting" pseudoscope. 
 
 The "reasoning", that is, handling of words, which 
 you have employed and which has just been referred to 
 again, ought to make it plain to you that all possible 
 pseudoscopes must belong either to the one or to the 
 other of only two chief dosses. That is, either the profile 
 of each eye's image is reversed in a lateral sense; or 
 the profiles are left unaltered, but that of each eye is 
 given to the other eye. No third class is thinkable co- 
 ordinate with these two classes of pseudoscopes. 
 
 If you are familiar with the appearance of images on 
 the photographer's ground glass plate, this might sug- 
 gest to you the construction of a third kind of pseu- 
 doscopic instrument, subordinate to the first of the two 
 classes just mentioned. Ask the instructor to show you 
 a "lenticular pseudoscope", and use it on your partner. 
 
PSEUDOSCOPY 81 
 
 Now try again a little "reasoning". In the first of 
 those two paragraphs on page 258, make your partner 
 exchange the words "right" and "left" everywhere no 
 matter what their connection. How does the resulting 
 statement compare with the unaltered statement of this 
 same paragraph, and how with the unaltered statement 
 of the other paragraph 1 Do you expect your partner to 
 act " pseudoscopieally " in such a case? 
 
 You can make the demonstration corresponding to 
 this "reasoning" by giving your partner both a pseu- 
 doscope of the first class and a pseudoscope of the second 
 class to look thru at the same time, in combination. 
 (You can also make the demonstration by standing your 
 partner before the target table so that a mirror on the 
 wall is about half way between him and the table and 
 parallel to the line running from him to the table. Then 
 make your partner see the table, not directly, but in the 
 mirror. If you are fond of geometrical drawings, prove 
 that you have then a combination of both pseudoscopie 
 effects, that is, a double reversal of habits and thus no 
 change of habit at all. But if you are not fond of geo- 
 metry, we do not require you to do it.) 
 
 Now select whatever pseudoscope you have come to 
 like best and let your partner look at the truncated hol- 
 low cone with which you are already familiar. Ask him 
 if the pseudoscope does not make the cone (quite aside 
 from the pseudoscopie effect) more deserving of the 
 name of (whatever the case may be) either "nearly 
 cylindrical" or "nearly funnel-shaped" than it would 
 nornwdly be. Explain that fact by recalling what you 
 learned from demonstration X. (What changes in "size"" 
 make a funnel out of a cylinder?) 
 
82 PSYCHOLOGY DEMONSTRATIONS 
 
 XV. Bright-Dark. 
 
 Read to your partner what you find about the Bright- 
 Dark substance (or Black-White substance, — it means 
 the same) on page 264 of your text. Then cut out of 
 black paper a parallelogram about an inch or two wide 
 and about four inches long. Then cut from the center 
 of this a smaller parallelogram so that a kind of black 
 frame of about % inch solid width remains. Fold 
 the shorter pieces (the ends) of this frame upon them- 
 selves to stiffen them. Then fasten one of the long 
 pieces of the frame with pins upon black velvet cloth 
 lying on the table, and bend the other long piece slightly 
 up so that you can easily slip a piece of paper under it. 
 Put a pin in the center of the frame and order your 
 partner to look steadily at the pin-head and to continue 
 doing that no matter what you do or ask him. 
 
 "While he is thus engaged, slip a piece of white paper 
 larger than the frame under the free half of the frame, 
 about as far as that pin-head. Slip out the white paper 
 again. Slip it under again. And so forth repeatedly. 
 See if you can do this fast enough or slowly enough — 
 experiment! — to induce your partner to say that the 
 one half of the frame "differs" from the other half "in 
 darkness" whenever the white paper is slipped under. 
 
 What statement made on page 264 is demonstrated by 
 that action of your partner which you have just called 
 forth by your manipulations and your questioning ? 
 , What two regions of the large part of the moon un- 
 illuminated by the sun — compare page 363 of your text 
 — correspond to the one and the other half of your dark 
 paper frame? 
 
BRIGHT-DARK 83 
 
 In spite of the "opposition" of the Dark (or Black) 
 excitation and the Bright (or White) excitation, these 
 excitations are not antagonistic to each other in the 
 sense that one would cancel or destroy the other and 
 the one alone would be left. On the contrary, they 
 are capable of coexisting in one and the same sensitive 
 cell, as can be proved by the fact that in such a ease 
 the name of "similar" can, in comparison with the cells 
 where they coexist, be applied to both the excitations in 
 sensitive cells where the Dark excitation alone occurs 
 and the excitation in sensitive cells where the Bright 
 excitation alone occurs. You will now demonstrate this 
 on your partner. 
 
 Take a small disk of, say, 2% inches diameter and of 
 rather dark (vulgarly speaking black) paper. This will 
 serve as the stimulus for those sensitive cells where you 
 want the Dark excitation alone to occur. Put this disk 
 on another disk of 4 inches diameter and composed of 
 a black and white sector. Put this combination of the 
 2% inch and the 4 inch disk on a third disk of 514 inches 
 diameter and of white paper. The white ring left free 
 of this largest disk will serve as the stimulus for those 
 sensitive cells where you want the Bright excitation 
 alone to occur. When you spin the set, you give your 
 partner three rings to look at. The smallest disk also 
 appears as a ring, for the brass screw of about 1 inch 
 diameter covers the center. Each of these three rings 
 is about Yi inches wide. 
 
 The middle one of the three rings is the one about which 
 we asserted that your partner might call it similar to " 
 both the outer, bright ring and the inner, dark ring. If 
 our assertion is true, we can also express it by saying 
 
84 PSYCHOLOGY DEMONSTEATIONS 
 
 that "obviously the two excitations Dark and Bright in 
 spite of their opposition, the first mentioned fact, are 
 not antagonistic in the sense of exclusiveness, but, second 
 fact, are capable of coexisting in one and the same sen- 
 sitive cell. 
 
 Demonstrate this on your partner by instructing him 
 to adjust the white sector and the black sector of the 
 middle ring until he is willing to say that the result is 
 equally similar (or equally dissimilar) to both the white 
 and the black ring, that is, until he can no longer say 
 that the resulting gray resembles one of the two other 
 rings less than it resembles the other. It is clear that, 
 as soon as your partner has called the gray "equally 
 similar" to the white and the black, he has also ad- 
 mitted that it is perfectly sensible to call it "similar" 
 to the white and the black. 
 
 Recalling again what you did in demonstrating the 
 "opposition" of the Dark and Bright excitation, you 
 ought to impress upon your memory that this "opposi- 
 tion" goes among psychologists often under the name 
 of Dark-Bright contrast, and also under the name of 
 Dark-Bright induction. Adopting the latter term, you 
 can restate the description of the demonstration just 
 made on your partner with the rings of the color-wheel, 
 by saying that the Bright excitation and the Dark ex- 
 citation "mix", or that a gray is "a mixture" of color- 
 less dark and bright (or "a mixture" of black and 
 white), in spite of this mutual induction. You may 
 wonder why your teacher or the author of this text 
 makes such a statement, which is "so obvious". You 
 will convince yourself in demonstration XVI that this 
 is "not so obvious", for you cannot state the same for 
 
BBIGHT-DARK 85 
 
 the Blue excitation and the Yellow excitation. You 
 will find there "no mixture" because of the mutual in- 
 duction. 
 
 Read now the first paragraph on page 290 of your 
 text and demonstrate, together with some of those facts 
 which you have already demonstrated, the "negative 
 after-images", so-called, resulting from exposure of your 
 partner's eye to black and white papers. (The "posi- 
 tive after-image" you will study in a later demonstra- 
 tion.) 
 
 Place a large sheet of white paper on the table. 
 Place the two halves of a sheet of black paper of similar 
 size so that between them a strip about half an inch 
 wide of the white paper is visible. Place a pin-head or 
 other small object on the white strip as a fixation mark 
 for your partner's eyes. I^ow let your partner keep 
 his eyes steadily on that mark for a considerable time. 
 "When he tells you that the black is no longer as dark 
 as it was at the first moment (compare "general adap- 
 tation" on page 291 of your text), remove the black 
 sheets. Ask your partner, before, not to move his eyes 
 from the mark if you should move the black sheets. Ask 
 him, now, while he keeps his eyes on the mark, to de- 
 scribe the appearance of the narrow strip. The nega- 
 tivity of the aiter-image of the narrow strip will prob- 
 ably be quite clearly expressed in the words which he 
 uses. Proceed in the same way except exchanging the 
 relative positions of black and white. Do both these 
 experiments over, but leave the papers untouched and 
 simply make your partner, when he has exposed his 
 eyes long enough, cover his eyes with his hands and 
 describe (with a little patience) the appearance of the 
 
86 PSYCHOLOGY DEMONSTKATIONS 
 
 after-image of the narrow strip. In order to give your 
 eyes a chance for rest, you and your partner may make 
 these experiments alternately on each other. The nega- 
 tivity of the after-excitation in these cases is theoretical- 
 ly much less plausible than the negativity of the ' ' succes- 
 sive induction" phenomena in demonstrations XVI and 
 XVII, where you will have true antagonism, while 
 between the Dark excitation and the Bright excitation 
 there exists, as already stated, no true antagonism, but 
 only a peculiar opposition. 
 
 XVI. The Antagonism, of Blwe and Yellow. 
 
 Read the lower half of page 277 and the whole fol- 
 lowing page of your text and then proceed in exactly 
 the same manner in which you proceeded in demon- 
 stration XV making up of Jjlack and white three equal- 
 ly broad rings, with this difference only that you use 
 blue instead of black and yellow instead of white. 
 Instruct your partner to adjust the sectors of the mid- 
 dle ring until lie is willing to say that the result is 
 equally similar to both the blue and the yeUow ring. 
 You will observe that he can not carry out your in- 
 structions, that he will never say that the result is 
 similar to both the blue and tlie yellow. He will al- 
 ways call it (more or less) similar either to one or to 
 the other, but never to both, — never both yellowish and 
 bluish. However, he can be made to say that the' re- 
 sult is similar to neither the blue nor the yellow, that 
 i.s. that the middle ring no longer deserves the name 
 "bluish" nor the name "yellowish" either, while hav- 
 ing a certain adjustment of its sectors. Let you'x 
 partner find this relation of the sectors and, in order 
 to have a definite record of what your partner has 
 
The Antagonism of Blue and Yellow 87 
 
 done, measure in hundredths the relative size of the 
 two sectors. 
 
 Now try to demonstrate on your partner what is de- 
 scribed on page 274 and on page 275 as far down as 
 "general adaptation". After having done this with a 
 large sheet of yellow paper, repeat the demonstration 
 with a large sheet of blue paper. 
 
 Read next the last two paragraphs on page 276 of 
 your text and try to demonstrate the facts mentioned 
 there. Put a piece of yellow or blue paper, two or three 
 inches in diameter, on a fairly colorless (fairly "neu- 
 tral", as we may also say) table and observe whether 
 your partner acts as your text states. 
 
 Now repeat the last demonstration with this differ- 
 ence. Pill the whole field of vision absolutely with 
 only one color, either yellow or blue. You can do that 
 best by taking a box, a little larger than your partner's 
 head, but having both the bottom and the lid removed. 
 For the bottom substitute a piece of transparent colored 
 glass. Then make your partner put his face into the 
 box while holding the box up conveniently with his 
 hands. Cover box and head with a large black cloth, 
 in the photographer's manner, in order to keep your 
 partner from seeing anything reflected on the glass, for 
 I'efleeted rays are not changed (filtered, colored) by 
 the glass. Then let him look out thru an open window* 
 upon a landscape containing houses, trees, streets and 
 a variety of other things. Wait patiently until your 
 partner has the experience, already demonstrated, of 
 "general adaptation". That is, you wait until he re- 
 ports that the originally quite discolored landscape be- 
 gins to look natural again. Then take the whole box 
 away and at that moment ask him whether the land- 
 
88 Psychology Demonstrations 
 
 scape immediately became discolored again, and in 
 what coloring. You have thus demonstrated again 
 •'successive induction". (By the way, do you recall 
 what other term, synonymous with successive induction 
 and found, for example, on page 291 of your text, you 
 used in demonstration XV?) 
 
 Read next page 277 of your text. Take a large gray 
 disk and place another disk, less than half the size, 
 and either blue or yellow, on the gray disk. Then 
 spin the whole set on the color-wheel. Instruct your 
 partner to keep his eyes steady on the center of the 
 wheel and to report to you the marginal effect on the 
 large gray ring. 
 
 Then demonstrate the same fact in such a manner 
 that two opposite margins overlap. Take a yellow 
 and a blue piece of paper, of note paper size or larger, 
 and let the edge of one lie on the other paper so that 
 there is nothing between the two colors. Then take 
 several strips of neutral gray paper, about % or %6 
 of an inch \nde, some darker, some brighter, prefer- 
 ably cut in zigzags or serpentines rather than straight, 
 and place them so that half of each is on the one, and 
 half on the other color. Cover the whole with tissue 
 paper and a,sk your partner what color names he would 
 give to those strips, and whether these names apply 
 only to the margins. 
 
 Demonstrate the same fact again as follows. Take a 
 yellow disk of 3^ inches diameter and place it on a 
 disk of 4 inches diameter composed of a large black 
 and small white sector. Then place the combination 
 again on a yellow disk, of 51/2 inches diameter, or lar- 
 ger. Spin the wheel and ask your partner what color 
 name he would give to the narrow ring composed of 
 
The Antagonism of Blue and YelijOw 89 
 
 a black and white sector. Let your partner adjust these 
 sectors to each other until he is more ready than ever 
 to apply that color name. Then spin on a second color- 
 v/heel a combination of black, white, and blue sectors 
 of any size disk, and have your partner adjust the 
 sectors so that he would call the color on this second, 
 solid-faced wheel a perfect match to the color of that 
 narrow ring on the first wheel. Measure, in hun- 
 dredths, the sectors of the second color-wheel and record 
 the values in your note book. You thus get a measure- 
 ment of the strength of the induction. 
 
 Do again what you were told in the lasit paragraph, 
 only using blue instead of yellow. By what names is 
 this phenomenon referred to in the middle of page 291 
 of your text? 
 
 Repeat the last two. cases, of a narrow gray ring on 
 a yellow or blue background, with very unsaturated 
 colors. For example, instead of two saturated yellow 
 disks use two disks of which each is a like combination 
 of only 25 per cent yellow and 75 per cent gray. Use 
 a gray of a brightness (of a "darkness", if you pre- 
 fer to say so) as near as you can find in the laboratory 
 gray paper disks dike the brightness (darkness) of 
 the colored paper with which you desire to combine it. 
 Spinning the wheel and matching the narrow ring's 
 color on a second wheel showing a solid face, how much 
 blue do you need on that second wheel ? Measure. You 
 will be surprized when you compare this with your 
 previous result at the strength of the color induction 
 even when the inducing color is rather unsaturated. 
 
90 Psychology Demonstrations 
 
 XVII. Bed-Green and the Entire System of "Sights". 
 
 That which "sounds" we call "a sound'-'. We need 
 in psychology a simple tenn for that which "looks". 
 Let us, as the heading suggests, call it "a sight". 
 
 Proceed exactly as you did in the first paragraph of 
 demonstration XVI, except that you substitute re'd 
 ior blue and green for yellow. Let your partner ad- 
 3ust the sectors of the middle ring until this ring is no 
 longer called by him reddish nor greenish either. Then 
 remove the largest and the smallest disk and retaiii 
 only the middle size disk composed of a red sector and 
 a green sector. Ask your partner if that ring, after 
 having thus become a whole disk which is neither red- 
 dish nor greenish, can be called colorless, a neutral gray. 
 If he replies in the negative, ask him further whether 
 he would prefer to call it yellowish or bluish. If he 
 prefers the former, give him a blue disk of the same 
 size (if he prefers the latter, then, of course, you give 
 him a yellow disk, — always the antagonistic color) and 
 let him add it as a third sector to the other two sectors, 
 the red aiid the green. 
 
 Now place the disk, composed of red, green and that 
 third color on a larger colorless disk of, say, 5% inches 
 diameter, composed of a white and a black sector. Spin 
 the whole and show your partner the gray ring sur- 
 lounding an inner, more or less colored field. If every- 
 thing you have learned theoretically about your part- 
 ner's visual sense (read especially page 281 of your 
 text) is correct, it must be possible to adjust the white 
 and black so to each other and also the inner three 
 sectors so among themselves that he will call the whole 
 disk, when spun, "homogeneous". Let him very care- 
 fully and patiently make these adjustments; and then 
 
The Antagonism of Ked and Green 91 
 
 measure the five sectors and write the result in your 
 note book in order to^ have a record of what you have 
 here demonstrated about the relation of the Red-Green 
 substance to the Blue-Yellow substance. 
 
 Read now the lower half of page 283 and all of page 
 284 of your text and then give your partner the four 
 (Why not six? And why is this question asl^ed?) 
 tasks, one after another, of producing on the color wheel 
 a dual color, in a middle ring, so that this dual color 
 resembDfis equully (no more nor less one than the other') 
 its two singular colors which are to appear on the in- 
 ner and on the outer ring. Choose the disks so that the 
 lliree rings are approximately of equal width. For ex- 
 ample, use diameters of 2J/^, 314, and 4 inches, or of 2V^, 
 A, and 5V2 inches. When your partner pronounces the 
 resemblajice equal, measure the sectors for your rec- 
 oj'd and proceed to the next of the four tasks. 
 
 Read now page 285 of your text and proceed to 
 demonstrate on your partner the necessity of using for 
 The representation of the entire system of ' ' sights ' ' a 
 graph or model of three dimensions. In order to dem- 
 onstrate this you must obtain a small disk of a satu- 
 rated color (choose a dual color, in order to get rid 
 of *the idea that for demonstrations of the system of 
 "sights" you are restricted to the use of singular col- 
 ors) ; place this on a larger disk composed of two sec- 
 tors, one of the same saturated color and the other sec- 
 tor a gray neither much darker nor much lighter than 
 it ; and place this set again on a larger disk of the same 
 gray. The absolute size of the triple disk does not mat- 
 ter; but make the three rings approximately equally 
 wide. Spin. Ask your partner to locate that line (that 
 is, the two end points of that straight line) on which 
 
92 Psychology Demonstrations 
 
 the three "sights" of your color- wheel are ideally found 
 in the three octahedrons of your text and also in the 
 painted and hollow model ia the laboratory. 
 
 In the preceding paragraph, however, you have not 
 yet demonstrated the necessity of using a graph or model 
 of three dimensions. Your partner could still locate 
 every name used by him within the color square. But 
 give your partner now two black disks to substitute 
 for the two gray disks of the preceding paragraph and 
 let him spin these on the color- wheel; give him also 
 two white disks and two colored disks as before, to 
 spin on a second color-wheel. Ask him -to vary the 
 sectors of the middle ring on both wheels to suit himself 
 and then to locate the line for the one wheel and for the 
 other wheel on which the "sights" of each wheel are 
 ideally found in the octahedrons and in the model. Now 
 he can abstain from using a, third dimension of the 
 graph or the model only if -he is willing to restrict him- 
 self to the single chosen color. In the preceding para- 
 graph he remained within two dimensions no matter 
 how many different colors he desired to use. 
 
 Before you dismantle the two wheels used in the last 
 paragraph ask your partner whether the coloring of 
 the middle ring is as easily detected in mixing 10 per 
 cent color -Rith 90 per cent black as in mixing 10 per 
 cent color with 90 per cent white. 
 
 Now read the last paragraph of page 286 of your 
 text. Ask the instructor for a gray screen with a half 
 inch hole and a horizontal scale (a campimeter or peri- 
 meter) ; also for a head-rest, a pointer, and four sheets 
 of paper : orange, violet, olive, and peacock. Fix your 
 partner's head so that, if he now looks thru that hole, 
 he sees the space of the hole completely filled in with 
 
The Entire System of Sights 93 
 
 the color of one of those sheets. The sheet must be 
 well illuminated and have no shadow on it. Therefore 
 keep yourself as well as other things out of the light. 
 Arrange the gray screen so 'that its scale lies on the 
 right, provided your partner intends to use his right 
 eye ; think it over and convince yourself that, other- 
 ynse, when your partner looks at different points of 
 the scale, the hole might fall on the blind-spot of his 
 right eye. Let the perpendicular distance from the eye 
 to the campimeter be about six inches and keep this 
 distance constant during all the tests. 
 
 Now ask your partner to close has left eye and to turn 
 Lis right eye along the scale until the hole becomes in- 
 visible. Put your pointer at this point of the scale and 
 move it slowly along the -scale toward the hole until 
 your partner, who follows your pointer with his eye, and 
 who is not permitted meanwhile even to glance at the 
 hole, tells you that the hole has not only become visible 
 (it will first appear as a neutral gray), but that it has 
 just taken on a definite singular color. Record that 
 point of the scale in your note book. 
 
 Continue moving your pointer with a speed which 
 your partner finds agreeable, until he telh, you that the 
 hole has just taken on the dual color to be expected. 
 Record that point of the scale. 
 
 Repeat the same procedure with the other three sheets 
 of colored paper which we selected. 
 
 Now put your pointer near the hole and ask your 
 partner, who follows the pointer with his eye, to stop 
 your motion of the pointer receding from the hole by 
 telling the very moment when the dual color changes 
 to a singular color. Record the distance from the hole 
 as measured on the scale. 
 
94 Psychology Demonstrations 
 
 Continue moving your pointer at a suitable speed 
 tmtil your partner tells you that the singular color 
 of the hole has just given way to a neutral gray. Rec- 
 ord that point of the scale. 
 
 Repeat the same procedure with the other three sheets 
 of colored paper. 
 
 Take now the average of the eight scale points at 
 which the changes occurred between a dual and a sing- 
 ular color. Take further the average of the eight scale 
 points at which the changes occurred between a singular 
 color and a neutral gray. These two averages give you 
 &n idea of the relative extent of the inner area of the 
 dual colors and the surrounding area or zone in which 
 only the singular colors blue and yellow are easily 
 recognizable. 
 
 That the eight measures giving each average vary 
 as much as you will probably find them to vary, is due, 
 firaong other facts, to the fact that the Red-Green sub- 
 stance and the Blue-Yellow substance do not have a 
 very sharp border line, but fade out somewhat gradually 
 from more central to more peripheral parts of the re- 
 tina. 
 
 If you have a clever partner and are yourself clever 
 enough, you may devise a method of demonstrating also 
 the fact that, when a dual color stimulus passes out of 
 your partner's blind-spot, ho is likely to give it first the 
 name of a singular color and then only the name of a 
 dual color, just as on the passing of a stimulus from 
 The peripheral to the centi-al regions of the retina. But 
 this demonstration is much more difficult and we do not 
 urge you to undertake it. 
 
 Now we are going to give you six tests in order to find 
 out what you have learned in demonstrations XV, XVT 
 
THE ENTIRE SYSTEM OF SIGHTS 95 
 
 and XVII about humaj^i reactions to qualitatively vary- 
 ing sights. Perform the foUo'wing six tasks and tell 
 m your note book exactly how you performed them. 
 
 (1) Match in darkness-hrightness two equally broad 
 lings of the color-wheel, — one ring being any (singular 
 or dual, to suit yourself) saturated color which happens 
 to be a rather dark color whenever saturated, and the 
 other ring being such an unsaturated color (singular or 
 dual) as happens to be a rather bright color whenever 
 saturated, but which you have darkened by the addi- 
 tion of a black sector for the sake of matching. 
 
 (2) Match in darkness-brightness two equally broad 
 rings of the color- wheel, — one ring being any (singular 
 or dual) saturaded color which happens to be a rather 
 bright color whenever saturated, and the other riii"' 
 being such an unsaturated color (lingular or dual) 
 as happens to be a rather dark color whenever satur- 
 ated, but which you have brightened Ijy the addition 
 of a white sector for the sake of matching. Why is 
 the regular octahedron only an approximation to the 
 true form of the color pyramid? 
 
 (3) Let three equally broad colored rings of the 
 color wheel dijfer only in darkness-brightness (not dif- 
 i'er also in coloring nor in saturation either). Use for 
 the intermediate ring a 50^ sector of gray, for the 
 inner and outer sector black (for either one) and white 
 (for the other sector), — ^black and white in quantities 
 to be found by matching the degree of saturation of 
 the three rings. What quantities did you use? And 
 on what line, parallel to what, are these three points 
 in the octahedron? 
 
 (4) Repeat what the last paragraph instructed you 
 to do, with this exception that, if you used then a singu- 
 
96 PSYCHOLOGY DEMONSTRATIONS 
 
 lar color, use now a dual color; or, if you used then a 
 dual color, use now a singular color. 
 
 (5), Let three eqiuMy broad rings differ strikingly 
 in color, but not at all in darkness-brightness ; and pay 
 no attention whatsoever to the question how saturated 
 the colors are, save that one (only one) of the rings 
 must have its maximum of saturation. 
 
 (6) Repeat what the last paragraph instructed you 
 to do, with .this exception that, if you used then a ma- 
 jority of singular colors amOng the three, use now a 
 majority of dual colors; and if you used then a major- 
 ity of dual colors, use now a majority of singular colors. 
 
 XVIII. Some Ghosts. 
 
 It goes without saying that the marginal effects of 
 local adaptation, and still more the negative after- 
 images, and most the positive after-images have been 
 occasions, in the history of mankind, for "seeing 
 ghosts". A person who stares at another person (re- 
 member what you have learned in demonstration V and 
 on pages 249 and 291 of your text as to whether such 
 a functioning of humian eyes is normal or not) may 
 very well see the other person surrounded by an "aura". 
 An after-image is still more likely to be regarded as 
 i\ ghost by superstitious people than a simultaneous 
 outer margin of a person's figure. Therefore the title 
 of this chapter. Demonstrate now a few particularly, 
 striking cases of successive induction of sights. 
 
 Take your partner into a room which has only one 
 window. Let him look steadily for about a minute at 
 the window cross or simply at a definite point of the 
 cross-bar of the two sashes if there is no cross. Then 
 make him cover his eyes with his hands, keep his eyes 
 
SOME GHOSTS 97 
 
 steady, and report to you during the next minute what 
 things there are visible. Now read the last paragraph) 
 on page 290 and the first paragraph on page 291 of 
 your text. If your partner has not reported to you 
 everything mentioned there, repeat the experiment and 
 make him look at that "Vidndow cross twice as long. 
 
 Now take your partner into a perfectly dark room and 
 keep Mm in the dark tAvo or three minutes, until his 
 eyes have become sufficiently adapted. Then tell him 
 to look in the direction in which he knows there is an 
 electric fixture. Turn on the light of a single bulb, and 
 after your partner has looked at it for a short time 
 turn off the light again. Ask him to report whatever 
 there is now visible, patiently. If his answers do not 
 satisfy you, repeat again as in the preceding paragraph. 
 "WTiile still in the dark, move a glowing match in a 
 circle or in other curves. Your partner's reports will 
 help you to answer the question: "Why do shooting 
 stars always have a tail?" 
 
 Now go to a dark room where you have a "Hering 
 window", that is, no other illumination than that which 
 comes thru two parallel narrow slots six or twelve inches 
 apart, one having a colored, the other a ground glass 
 pane. Use a parallel ruler and throw four shadows, 
 close together, on a white or gray sheet of paper con- 
 veniently arranged opposite the window. Two of these 
 shadows (which?) ought to be colorless; but. they are 
 not. And the ghost-like aspect of the case consists in 
 the fact that, if the relative width of the window slots 
 is well adjusted to the transparency of the gla^s, your 
 partner can not tell which two of the four colored 
 shadows are the real things and which two are the 
 ghosts. So you see that there may be some excuse for 
 
1)8 PSYCHOLOGY DEMONSTRATIONS 
 
 the reports of some people in the histoiy of maiikind 
 that ghosts had really made their appearance. 
 
 A somewhat similar and again ven- striking dem- 
 onstration is that made with tine rings in tlie box which 
 you will now obtain from your instructor. Some of 
 these rings are strongly colored because no white light 
 is reflected on them. They ' are, so to speak, shaded. 
 Some others ought to be virtually colorless because no 
 light ("no-light" e(|nals black) is sent thru the light 
 sifting and thus color producing glass. If these latter 
 rings appear colored, tliey deserve to be called ghost 
 colors. You will find again that your partner, if the 
 adjustments are well made, can not tell which are the 
 real colors and which the cjJiost colors. 
 
 There is a fiurnmatwn of tiro effects, (1) the bright- 
 dark opposition, or call it contrast, between the shaded 
 and the non-shaded portions of the background, whicli 
 becomes here a phenomenon of nervous deflection witli 
 consequent failure to react to the existing color exci- 
 tation of the non-shndcfl background portions, and (2) 
 local adaptation for the alternating rings. It is this 
 sv)iimaiion which makes the ghosts in this case and even 
 m,^re in that of the Hering window so realistic. Tf 
 tJiere were an adequate motor reaction to the color big 
 of the whole background, too, the ghost would be 
 much less realistic. 
 
 XIX. To)ie Ivduclidii und Whal it is Good For. 
 
 When there are currents of electricity A\'here nobody 
 poured out any, we speak of electricity by induction. 
 When there is color according to your partner's testi- 
 mony, altho you did not in any sense pour out any color ■ 
 there, yon speak of color by induction. You might then 
 
TONE INDUCTION 
 
 99 
 
 .^ery well accustom yourself also to speak of tone by 
 induction, when your partner reports the presence of 
 a tone altho you did not pour out any such tone, while 
 indeed pouring out other tones. Electricity may in- 
 duce electricity, color may induce color, tone may in- 
 duce tone. 
 
 Read to your partner what you find about tone in- 
 duction in the last paragraph on page 307 of your text. 
 Then sound the two Galton whistles by filling the large 
 bellows completely with air and letting the bellows go 
 down without working it, in order to avoid every dis- 
 turbance by noise. Fill again and let down again. And 
 so forth. The bellows, being large, gives air for a con- 
 siderable time when completely filled. 
 
 Sound a tuning fork (one of 300 full, so-called double, 
 vibrations will do) by tapping it gently with your finger 
 or a felt hammer, and ask your partner to remember 
 the tone. Let him hum the tone if he wishes. Then 
 stop the fork by touching it, and make your partner 
 change one of the whistles until the induction tone is 
 just like the tone he was humming. He can not do 
 that while the fork is sounding, because the fork tone 
 would "swamp" everything. There is no danger that 
 your partner might confuse one of the two whistle 
 tones with the induced tone. The latter, even if out of 
 tune with the fork tone and much higher, is too mellow 
 to be mistaken for the exceedingly high, very shrill, 
 tones of the Galton whistles. "Shrill", however, does 
 not meaa very loud, but "sort of pointed". Thus 
 your partner's task consists only in listemng to the 
 induced tone and making it eqiml to the tone he ivas 
 or is humming. 
 
 By the way, if you have studied physics, we must 
 warn you against confusing a certain physical phenom- 
 
100 PSYCHOLOGY DEMONSTRATIONS 
 
 enon with what we have called an induction tone, that 
 is, with an "induced" sensory and nervous excitation. 
 You find in the literature of physics frequent references 
 to "combination tones, summation tones, difference 
 tones, asymmetry tones" and other acoustic phenomena 
 of a similar kind. These are all characterized by the 
 fact that some unsymmeirical elastic body, a certain 
 reed, a certain air volume, an auditory tympanum, an 
 auditory o.«sicle in its peculiar bearings, etc., is forced 
 at some time to vibrate with unusual vigor; and then 
 certain phenomena occur, deducible from differential 
 equations, not incomparable to the planetary aberra- 
 tions of the astronomers. The not infrequent confusion 
 is due to the fact that the induction tones are also a 
 kind of difference tones. Look again at page 307 in 
 order to tell why they may also be called difference 
 tones.) 
 
 Since the induction tone is a kind of difference tone, 
 you can tell by "reasoning" (remember chapter XVI 
 of your text) that there must be a second position of 
 the piston of the same whistle when the induction tone 
 will be exac^tly the same. Find that second position, 
 ilake your partner turn the piston so that the induced 
 tone becomes lower. Make him continue turning, very 
 slowly, in the same direction, while he reports to you 
 that the tonie becomes still lower, momentarily dis- 
 appears,, then reappears very low, then rises more and 
 more and finally again equals the fork tone. Aside 
 from being good practice for your partner and satis- 
 fying your natural curiosity this procedure of finding 
 the second position has no particular virtue. 
 
 When the induced tone is well tuned and in unison 
 with the fork tone, your partner ought to report that 
 
TONE INDUCTION 101 
 
 there are "beats", provided the simultaneous fork 
 tone is neither too strong nor too weak. The intensity 
 has to be tried out. They are irregular beats on ac- 
 count of the slightly inconstant air pressure in a col- 
 lapsing vessel made of wood and leather. Such slow 
 beats may be used by your partner as an indiaation that 
 he has about finished what you asked him to do. Such 
 slow beats are therefore of great practical value to the 
 professional tuner of instruments. 
 
 An interesting variation of this procedure,, of dem- 
 onstrating an induced tone by having somebody tune 
 it, is the following. You take two tuning forks, say, 
 of 600 and of 525 (complete) vibrations. You bow these 
 forks with a bass bow to make them sound very strong- 
 ly and keep them sounding very strongly. This re- 
 quires some skiU in handling the bow without tearing 
 the horse hairs by letting the hairs slip off the end 
 of the tine which you are bowing. (You never touch 
 more than one tine.) Keep at a safe distance (about 
 1/2 inch) from the end of the tine. 
 
 Now give your partner a big tuning fork with ad- 
 justible weights, variable between, say, 60 and 100 vi- 
 brations, and tell him to adjust the weights until the 
 tone of this big fork is equal to the induction tone of 
 the two smaller forks which you keep sounding. Do 
 not separate the weights mu.ch from each other; if you 
 do that, the fork will not sound well. Your partner 
 • should again utilize the beats, which in this case will 
 fortunately be very regular, in order to notice that he 
 is approaching the goal which you have set for him. 
 < Tell your partner to show, by beating the air with 
 his finger, the exact tempo of the beats. Then let him, 
 by tuning the big fork, slow up the tempo of the beats 
 
102 PSYCHOLOGY DEMONSTRATIONS 
 
 until there are no beats left. This is good practice, 
 helpful in the task of tuning at any later time any mu- 
 sical instrument. 
 
 Now let your partner apply his knowledge of the 
 iaduction ("difference") tones to the very practical 
 problem of finding the ratios in which the tones of the 
 white keys of a certain stop of the laboratory organ 
 are tuned. If we could afford to have you and your 
 partner tune the organ, this would be still more inter- 
 esting. But since in all probability you would rather 
 mistune it, we restrict you to finding oui in what ratios 
 it actually is tuned. Start with the ratio of a high f 
 to the following g, and determine all the ratios as far 
 as the next f. 
 
 First sound steadily f and g simultaneously, and let 
 your partner, listening to the low induction tone all the 
 time, discover what tone that induced tone is by mo- 
 mentarily pressing down one of the white keys on the 
 left of the keyboard. That is, your question is: If 
 g — f = X, what is X? Your partner tells you. Then re- 
 member that the ratio of octave tones is always 1:2, 
 and try to express x as a function of either f or g. As 
 soon as you have substituted this in the above equation, 
 you can, after dividing the whole equation by f, answer 
 the question: What is the ratio g:f numerically? Your 
 first problem is solved. 
 
 Now sound steadily a and g, and let your partner 
 discover what white key on the left of the keyboard is 
 X in the equation a — ^g=x. Then try to express x in 
 this equation as a fimction of g (remembering the re- 
 sult of the preceding paragraph, without which you 
 could not do it). Divide the whole equation by g and 
 aaswer the question : What numerical value do~ yon 
 get for the ratio a:g? Your second problem is solved. 
 
TONE INDUCTION 103 
 
 111 a similar maimer determine the ratios b :a, c :b, d-.e, 
 e :d, f :e. You will then have a definite idea as to 
 liQW an organ tuner would proceed, when the reeds or 
 pipes are still untuned, but the ratios are given to him. 
 You notice that the existence of the induced tone has 
 n high practical value. 
 
 XX. Voiced and Voiceless Speech Sounds. 
 
 The following demonstrations may be more striking 
 if you can make them on your partner before he has 
 read thie following list of words. The demonstration 
 may be quite successful, however, even if he' has already 
 read the words in the Kst. Besides, it is always pos- 
 sible for you to try the same demonstration on some 
 friend who is not one of your classmates and who is 
 unacquainted with the list. 
 
 In order to understand what you are going to dem- 
 onstrate, read pages 313 to 819 of your text. 
 
 Give your partner a sheet of paper and ask him to 
 v.Tite down quickly, without hesitation, the nuinber and 
 the word which he understands whenever you pronounce 
 a cardinal number (from 1 to 50) and the word in the 
 list belonging to it. However, instead of making him 
 write the whole word, be satisfied if, in order to save 
 time, he writes only the first two or three letters, just 
 enough for later identification. 
 
 Now read to him the list, carefully observing every 
 condition below mentioned. (1) Be sure that you 
 whisper, that is, that your larynx is wide open all the 
 time and never offers the slightest avoidable obstruc- 
 tion to the passage of the air. (2) Do not try to speak 
 loud, for, if, you do try, you will surely not whisper. 
 But be sure that vou do not make the first sound of 
 
104 PSYCHOLOGY DEMONSTRATIONS 
 
 each word (correspondinR- to the l)lack-faced letter) 
 weaker than the following pai'ts of the word. Rather 
 give the black-faced part of tJie vmrl more emphasis 
 than the others. But remember always that the whole 
 word is to be whispered. 
 
 The experiment, in addition to its demonstratioual 
 value, will serve you as a test of your ability to carr>- 
 out the instructions given above. The fewer errors 
 >our partner shows in nnderstandin"' you, the less cap- 
 able you are in following those insti-uctions. 
 
 Do not wait long after haying pronounced each word. 
 Give your partner barely time enough to jot down th,e- 
 number and two or three letters before you give the 
 next number and the next word. When you have fin- 
 ished the fifty words, compare your partner's list with 
 your list of words. Mark in your partner's list all the 
 words misunderstood. A comparison, then, of the words 
 misundei-stood with those well understood ought to re- 
 veal clearly what speech sounds ("letters", as we 
 vulgarly say) of the English language can not be pro- 
 duced uidess tliey are voiced. 
 
 I. smith 14. vile 
 
 2. plumber 15. rooster 
 
 3. carpenter 16. grow 
 
 4. dinner 17. gill 
 f). sick 18. joke 
 
 6. veal 19. rope 
 
 7. light 20. span 
 
 8. bride 21. stake 
 
 9. write 22. dent 
 10. woo 23. hound 
 
 II. zeal 24. whip . 
 
 12, boast 2."). wine 
 
 13. letter 26. die 
 
VOICED AND VOICELESS SPEECH 
 
 105 
 
 27. 
 
 bull 
 
 28. 
 
 bush 
 
 29. 
 
 meat 
 
 30. 
 
 eat 
 
 31. 
 32. 
 
 junk 
 mouth 
 
 33. 
 
 nose 
 
 34. 
 35. 
 
 gin 
 milk 
 
 36. 
 
 cheese 
 
 37. 
 
 38. 
 
 girdle 
 fish 
 
 39. river 
 
 40. Greek 
 
 41. Chinaman 
 
 42. Russian 
 
 43. dirk 
 4jL fork 
 
 45. knife 
 
 46. apple 
 
 47. gore 
 
 48. furnace 
 
 49. goal 
 
 50. bowl 
 
 NoAv tell your partner that you are going to pro- 
 uounce flic sound of ten letters (be sure not to pro- 
 nounce the "names" of the letters, but their sounds; 
 compare page 376 of your text) and that you want him 
 unhesitatingly to write downa, after each number from 
 51 to 60, one word which either begins or ends (prefer- 
 ably hegiits) i^dth that particular speech sound. Again 
 you pronoimce both number and letter sound tchisper- 
 ing, with your larynx wide open. However, altho 
 whispering, put a considerable degree of emphasis on 
 each letter sound. Compare your partner's list of ten 
 words with your list of letters and draw yoiir own 
 conclusions. Blow vour nose before von start. 
 
 51. 
 
 V 
 
 52. 
 
 b 
 
 53. 
 
 w 
 
 54. 
 
 z 
 
 56. 
 
 J 
 
 57. 
 
 d 
 
 58. 
 
 m 
 
 59. 
 
 n 
 
 60. 
 
 ng 
 
 55. ga 
 
 Now tell your partner to write dawa three more words 
 beginning or ending with the three sounds yovi give 
 
106 PSYCHOLOGY DEMON STRATIONS 
 
 him. In this case you not only whisper, but also hold 
 your nose tightly closed. 
 
 61. m 62. n 63. ng 
 
 And finally make him write one more -word in the 
 same manner. In this case, while you do not whisper, 
 you hold your nose tightly closed. 
 
 Gi. ng 
 
 The student should carefully detacli, when he needs 
 them, the entry blanks following the index of this book, 
 and use them in -m-iting up the demonstration to which 
 each belongs, pasting them (not pinning or clipping) in 
 the report which he hands in to his teacher. 
 
 The ApparatiLS Needed for the Demonstratioixs described 
 in this book is obtainable from C. H. Stodting Co., 
 3037-3047 Can-oil Avenue, Chicago. 
 
INDEX 
 
 Accommodation 34, 75. 
 Adaptation 85, 87, 96. 
 Adjusting 24, 25, 34, 49, S3. 
 After-images 42, 85, 86, 96, 
 
 97. 
 Angles 45. 
 Animals 16. 
 Antagonism 86, 90. 
 Antagonistic colors 66. 
 Architecture S3. 
 Artificial blind-spots 56, 59. 
 Asymmetry tones 100. 
 Aura 96. 
 
 Average 7. , 
 
 Beats, use of, 101. 
 Binocular vision 60. 
 Black 82. 
 
 Blind-spots 54, 93, 94. 
 Brain 39. 
 Bright 82, 95. 
 Campimeter 92. 
 Causes 11, 37. 
 Choice reaction 4, 8. 
 Colors, antagonistic, 66. 
 Colors, dual, 91, 93, 9 1. 
 Colors, similar, 67. 
 Colors, singular, 91, 93, 94. 
 Combination tones 100. 
 Competition, law of, 62-64. 
 Compromise 18. 
 Condensation, nervous, 36, 39, 
 
 40. 
 Conductivity 9, 37, 39. 
 Consciousness 2, 37. 
 
 Contrast 84, 98; 
 
 Convergence 75. 
 
 Dark 82, 95. 
 
 Definition of Psychology 25. 
 
 Deflection 25, 38, 64, 98. 
 
 Delayed reaction 36-39. 
 
 Depth 34-36. 
 
 Deviation, average, 7. 
 
 Difference tones 100, 102. 
 
 Dimension 22. 
 
 Dual colors 91, 93, 94. 
 
 Duration 11. 
 
 Ebbinghaus 11. 
 
 Effect, law of, 11. 
 
 Error 19, 20, 23, 32. 
 
 External factors in habit , 
 
 formation 12-14. 
 Eyeball 25. 
 
 Eye movement 26, 48. 
 Frequency, law of, 11. 
 Ghosts 42, 96. 
 Gloss 63, 64, 66. 
 Habit formation 9-14, 65. 
 Habits 47, 49-51, 5S, 56, 58, 
 
 65, 69, 75, 81. 
 Hering window 97, 98. 
 Illusion 22, 45-54. 
 Imagination 59, 60. 
 Induction, color, 84-86, 88, 89. 
 Induction, tone, 98. 
 Introspection 3. 
 Kinesthetic 21. 
 Knowledge 39. 
 Larec-small 43-45, 81. 
 
 107 
 
103 
 
 INDEX 
 
 ' Larynx 103, 105. 
 Learning curve IS, 16. 
 .Localizing 22, 25, 27, 3', 35, 
 
 54. 
 Long path 9. 
 Magic 6. 
 Maze 13-16. 
 Mixture, visual, 84, 85. 
 Multiple habit 9, 12, 13. 
 Muscle tonus 37. 38. 
 -Nturamebimetcr 5. 
 Octahedron of sights 92. 
 Opposition of bright and 
 
 dark 83, 84, 86, 98. 
 Painters 67. 
 
 Paralla.x-stereograms T?-. 
 People 2. 
 Perception 48. 
 i'erimeter 92. 
 Perspective 46, 47, 49, 51-53, 
 
 •71. 
 Physiologist 25. 
 Plastographical views 72. 
 Preoccupation 37. 
 Pseudoscopes, two classes of, 
 
 80. 
 Pseudoscopy 45, 69, 73. 
 Psychanalysis 50, 51, 55, 64, 
 
 65. 
 Psychologist 25. 
 Reaction time 4. 
 Reading 26, 27. 
 "Ready" signal 23. 
 Real 97, 98. 
 Reasoning 77-8L 
 Reflex 9, 29. 
 
 Repetition in learning 11. 
 Resistance, nervous, 9, 10. 
 Resultant, lav^ of, 62. 
 
 Rhythm 29. 
 
 Rhythm test 30-32, 34. 
 
 Rhythm training 32-34. 
 
 Sense organs 25. 
 
 Shooting stars 97. 
 
 Short path 9. 
 
 Si-ghts 90, 96. 
 
 Sights, system of, 90-92, 95. 
 
 Singular colors 91, 93, 94. 
 
 Size 43-45, 81. 
 
 Sound localization 22. 
 
 Space 45. 
 
 Speech sounds 103. 
 
 Stereoscope prisms 72, Ti. 
 
 Stereoscopy 68. 
 
 Subdivided areas 53. 
 
 Substituted action 45, 46, 
 49-51. 
 
 Summation* tones 100. 
 
 Susceptibility 9, 10. 
 
 Teleology 11. 
 
 Threshold 16, 17, 19, 21, <1, 
 42. 
 
 Tones 98. 
 
 Tones, practical value of in- 
 duced, 102, 103. 
 
 Trick 6, 20, 56-58. 
 
 Tuner, instrument, 101-103. 
 
 Vesture 53, 54. 
 
 Visual localization 27, 34-36. 
 
 Voiced sounds 104. 
 
 Wasted habits and wasted 
 reflexes 43, 52, 75. 
 
 Weights 16, 17, 20. 
 
 Whisper 103-106. 
 
 White 82. 
 
 Will 39. 
 
 Zones, color, 94. 
 
To page IS. 
 
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To page 23. 
 
 Give each of the nine stimuli about ten times in irregular order. Re- 
 cord each judgment by mal<ing a little cross in the proper square. Pasle tliis 
 sheet in your note book. Translate your records into the table below Finally 
 make a general statement covering your results. 
 
 JUDGMENTS 
 
 R KB RF B Above F LF LB L 
 
 
 Total.. 
 
 1. Lefts (L, LF, LB) regarded as Rights (R, RB, RF) times. 
 
 2. Rights (R, RB, RF) regarded as Lefts (L, LF, LB) times. J 
 
 3. Fronts (F, RF, LF) regarded as Backs (B, RB, LB) or Above times.] 
 
 ^Total.. 
 
 4. Backs (B, RB, LB) regarded as Fronts (F, RF, LF) or Above times.) 
 
 5. Above called Fronts (F, RF, LF) or Backs (B, RB, LB) times. 
 
 G. Above called Rights (R, RB, RF) or Lefts (L, LB, LP) times. 
 
 7 Above judged correctly - - times. 
 
/ 
 
 
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 1 
 
 
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