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Boris Sidis, Ph.D.

© 1898. New York, D. Appleton and Company.




        IN our last chapter we ventured to generalize that every man in his full normal waking state is more or less suggestible. I should not wonder if such a seemingly sweeping generalization should startle many a cautious reader, and should call forth strenuous opposition. We must therefore rigorously demonstrate the fact of the universality of normal suggestibility. Such a proof is of the more importance, as the generalization which it establishes supplies a new principle to sociology, furnishes a key to the comprehension of many a great historical event, gives a deeper insight into the phenomena of political and economical life, and might possibly be of use in education. Is there such a thing as suggestibility in the normal waking condition? The Nancy school, with Bernheim and Liebault at its head, gives an affirmative answer. "Jemanden hypnotisiren," says Bernheim, "heisst nur: seine Suggestibilität künstlich erhöhen." In fact, the hypnotic state itself is induced by suggestion. "Es giebt keinen Hypnotismus: es giebt nur Phänomene der Suggestion," exclaims the Nancy professor. "Als etwas pathologisches, als eine künstliche Neurose betrachtet existirt ein Hypnotismus nicht. Wir schaffen im eigentlichen Sinne mit ihm keinen besonderen Zustand des Gehirns oder des Nervensystems; wir machen uns ganz einfach nur eine physiologische Eigenthümlichkeit des Gehirnsdie Suggestibilitätzu Nutze und schaffen die zur Entfaltung dieser Suggestibilität günstigen Vorbedingungen." On closer inspection, however, we find that the great authority of the Nancy school stretches too wide and far the conception of suggestion, for, according to him, "Jede Vorstellung ist eine Suggestion." This, I say, is too far-fetched; for it is to identify the whole field of mental activity with but a part of it, namely, suggestibility. This is, in fact, the obliteration of all traces of the problem itself. If now we turn and ask for facts that go to support his view, we find that Bernheim does not sustain his cause. He limits his instances to but a small class of persons who are easily suggestible in their waking state, but he offers no proof that suggestibility is present in all men. "Es giebt Menschen bei denen.  .  . die einfache Affirmation, ohne Schlaf und ohne vorhergehende ihn begunstigende Manipulationen bei ihnen alle sogenannten hypnotischen Phänomena hervorruft. Durch das einfache Wort schafft man bei ihnen Anästhesia, Contractur, Hallucillationen, Impuls, die verschiedensten Handlungen."1

        Although the instances Prof. Bernheim adduces do not certainly establish the fact of the universality of normal suggestibility, they are still interesting for us as they show the presence of normal suggestibility in some particular cases at least. "Many subjects," writes Bernheim in his Suggestive Therapeutics, "who have previously been hypnotized may manifest susceptibility to the same suggestive phenomena in the waking state, without being again hypnotized, however slightly might have been the influence of a small number of previous séances. Here, for example, is the case of K., one of my patients who is accustomed to being hypnotized, and is subject to light somnambulism. Without putting him to sleep, I say directly: 'Close your hand. You can not open it again.' He keeps his hand closed and contracted, and makes fruitless efforts to open it. I make him hold out his other arm, with his hand open, and say, 'You can not shut it.' He tries in vain to do so; brings the phalanges into semiflexion, but can do no more in spite of every effort. There is in my service a young hysterical girl afflicted with sensitivo-sensorial hemiamæsthesia of the left side, and capable of being hypnotized into deep sleep. In the waking condition she is susceptible to catalepsy or suggestive contraction. I can effect transfer of the hemianæsthesia from the left to the right side without hypnotizing and without touching her. In one of my somnambulistic cases I can obtain all possible modifications of sensibility in the waking condition. It suffices to say, 'Your left side is insensible'; then if I prick his left arm with a pin, stick the pin into his nostril, touch the mucous membrane of his eye, or tickle his throat, he does not move. The other side of his body reacts, I transfer the anaesthesia from the left to the right side. I produce total anæsthesia, which was on one occasion so profound that my chef de clinique pulled out the roots of five teeth which were deeply embedded in the gums, twisting them round in their sockets for more than ten minutes. I simply said to the patient, 'You will have no feeling whatever.' He laughed as he spat out the blood, and did not show the least symptom of pain."

        Here, as we see, the experiments were carried on with somnambulic and hysterical subjects; the result, therefore, can not prove the facts of suggestibility in normal and perfectly healthy people. Some of my own experiments might possibly prove more conclusive. Mr. W., an acquaintance of mine, who was never hypnotized by anyone, readily took suggestions in his waking state. I told him he could not write his name. He tried, and he did write it. I stretched out my arm, opened my hand and stiffened the fingers, and said, "Try now." He could not writehis hand became cataleptic. I made a whole series of experiments of this kind, but as they interested me from quite a different point of view I shall giye a detailed account of them later on. Mean while this one instance will suffice for our present purpose to show the power of suggestion in the waking state. The fact, however, of its rarity and singularity makes it unfit to prove the universality of normal suggestibility.

        In the Zeitschrift für Hypnotismus2 Prof. J. Delboeuf brings cases of suggestibility in normal condition. Thus he made a patient anæsthetic who was not and could not be hypnotized. He told the patient: "Reichen Sie mir Ihren Arm, sehen Sie mich fest an und zeigen Sie mir durch Ihren Blick, dass Sie entschlossen sind, nichts zu fühlen, und Sie werden thatsächlich nichts fühlen." The patient did it. Prof. Delboeuf severely pricked the subject's arm, and the latter felt no pain.

        To take another case. An old man of seventy suffered great pain from facial neuralgia for more than fifteen years. "lch komme zu ihm," says Prof. Deluoeuf, "ziehe ihn heftig am Bart und erkläre ihm, dass er keine Schmerzen mehr hat, dass er auch ferner keine Schmerzen haben wird, und meine Prophezeilmng erfüllt sich." These cases, like the preceding one, are subject to the same objections; they do not prove the universality of normal suggestibility on account of their rarity and singularity. Not everyone can so easily be made cataleptic or anæsthetic in his waking condition. With most people such suggestions are failures even in hypnosis. The only way, then, to test the verity of normal suggestibility is to lay aside all experimentation on hysterical, somnambulic, hypnotic, and extraordinarily suggestible subjects, and start a series of experiments on perfectly healthy and normal individuals. Thanks to Prof. H. Münsterberg and to the admirable facilities afforded by the Psychological Laboratory of Harvard University and the Pathological Institute of the New York State Hospitals, I was enabled to carry out more than eight thousand experiments relating to the subject of suggestion.

        The order of experiments taken up first was suggestion of letters and figures. The mechanism of this class of experiments was as follows: A successive series of letters or of figures was introduced through a slit on a white screen, each letter or figure being pasted on a separate slip of cardboard which in colour and position coincided with the background of the screen. Each experiment consisted of a series of nine slips. Each slip was kept on the background for two or three seconds. The interval between the slip and its successor was also two or three seconds. Time was measured by a metronome inclosed within a felt box, with a rubber tube passing close to the ear of the experimenter, so that the subjects should not be disturbed by the ticking of the metronome. For the same reason the experimenter and his movements of inserting the slips into the white screen were all carefully hidden by screens. The ring of a bell indicated that the series came to an end, and it also served as a signal for the subjects to write down immediately on paper which they kept ready in their hands anything that came into their mind at that particular moment―letters, numerals, words, phrases, etc.

        While looking for evidence for normal suggestibility, an opportunity was also taken to arrange the experiments according to different factors, so that should it be proved that suggestion in the normal state is an indubitable fact, we should be enabled to know what kind of factors are the more impressive and suggestive.

        The series of letters and figures were arranged according to the following factors and their combinations:

        1. Repetition.

        2. Frequency.

        3. Coexistence.

        4. Last impression.

        Great care, of course, was taken not to repeat the same series of letters or figures. As I had many slips at my disposal the series could be easily changed both by permutation and insertion of new slips. The subjects did not and could not possibly suspect the suggested letter or figure, first, because there were so many of them in each series; second, because the factors studied were constantly varied; and, third, because sham series, such as inverted or coloured letters, etc., were introduced so as to baffle the subjects.

        I had twelve subjects at my disposal, and experimented with three or four at a time. Recently I made experiments of this kind with thirteen subjects more, so that the total number of subjects is twenty-five.

        The results are as follows:

        1. REPETITION.In the middle of the series a letter or numeral was shown three times in successione.g.:

B 3
E 6
K 8
M 5
M      or      5
M 5
N 7
O 2
P 9

        Of 300 experiments made, 53 succeededthat is, the subject wrote the letter or numeral suggested by the factor of repetition.

        The factor of repetition gives a suggestibility of 17.6 per cent.

        2. FREQUENCY.A letter or numeral was shown three times in the series, and each time with an interruptione.g.:

B 5
K 3
E 7
K 3
M      or      9
K 3
C 4
R 8
D 6

        Of 300 experiments made, 128 succeeded.

        The factor of frequency gives a suggestibility of 42.6 per cent.

        3. COEXISTENCE.A letter or numeral was shown repeatedly; not, however, in succession, as it was in the case of the factor of repetition, also not with interruptions as it was in the case of frequency, but at the same timee.g.:

B 4
E 1
C 2
D 6
R R R      or      7 7 7
M 5
L 3
A 9
F 8


         Of 300 experiments made, only 20 succeeded.

        The factor of coexistence gives as its power of suggestion 6.6 per cent.

        4. LAST IMPRESSION.Here was studied the suggestibility effected by the last impression, by the last letter or figure. In all our experiments unnecessary repetition was carefully avoided. It is plain that the nature of these experiments of last impression required that not one letter or figure should be repeated twice in the seriese.g.:

A 7
K 9
F 5
L 8
D      or      6
R 2
B 4
E 1
M 3


        Of 300 experiments made, 190 succeeded.

        The factor of last impression gives a suggestibility of 63.3 per cent.

        5. COEXISTENCE AND LAST IMPRESSION.In these experiments a slip with three identical characters pasted on it appeared at the end of the series, thus combining in one the factor of coexistence with that of last impressione.g.:

E 2
N 5
C 7
K 1
B      or      9
M 8
Q 4
Z 6
A A A 3 3 3

        Of 300 experiments made, 55 succeeded.

        The combined effect of coexistence and last impression gives a suggestibility of 18.3 per cent.

        6. FREQUENCY AND LAST IMPRESSION.The letter or numeral repeated with interruptions was also shown at the end of the seriese.g. :

M 5
C 2
B 8
C 2
K      or      4
C 2
P 9
N 6
C 2

        Of 150 experiments made, 113 succeeded.

        The combined effect of the two factors gives a suggestibility of 75.2 per cent.

        Arranging now the factors in the order of their rate of effected suggestibility, we have the following table:


Per cent.
Frequency and last impression....... 75.2
Last impression................................ 63.3
Frequency......................................... 42.6
Coexistence and last impression... 18.3
Repetition.......................................... 17.6
Coexistence...................................... 6.6


        Comparing now the suggestibility effected by different factors,3 that of the last impression stands out most prominently. The "last impression" is the most impressive. Our daily life teems with facts that illustrate this rule: The child is influenced by the last impression it receives. In a debate he, as a rule, gains the victory in the eyes of the public who has the last word. In a crowd he moves and stirs the citizens to action who makes the last inciting speech. In a mob he who last sets an example becomes the hero and the leader.

        Frequency comes next to last impression and precedes repetition. This may be explained by the fact that in repetition the suggestion is too grossly obvious, lying almost on the surface; the mind, therefore, is aroused to opposition, and a counter-suggestion is formed; while in frequency the suggestion, on account of the interruption, is not so tangibly obvious, the opposition therefore is considerably less, and the suggestion is left to run its course.

        Coexistence is a still poorer mode of suggestion than repetition; it only arouses opposition. Coexistence is in reality of the nature of repetition, for it is repetition in space; it is a poor form of repetition.

        On the whole, we may say that in the normal state temporal or spatial repetition is the most unfortunate mode of suggestion, while the best, the most successful of all the particular factors, is that of the last impressionthat is, the mode of bringing the idea intended for suggestion at the very end. This rule is observed by influential orators and widely read popular writers; it is known in rhetoric as bringing the composition to a climax. Of all the modes of suggestion, however, the most powerful, the most effective, and the most successful is a skilful combination of frequency and last impression. This rule is observed by Shakespeare in the speech of Antony. Be these rules of the particular factors what they may, one thing is clear and sure: these experiments unquestionably prove the reality of normal suggestibility; they prove the presence of suggestibility in the average normal individual.

        From suggestion of ideas I turned to suggestion of movements, of acts. The first set of experiments was rather crude in form, but not without its peculiar interest and value.

        The experiments were carried on in the following way: On a little table I put a few objects, screened from the subject by a sheet of white cardboard. The subject was asked to concentrate his attention on a certain spot of the screen for about twenty seconds. On the sudden removal of the screen the subject had immediately to do somethinganything he liked. It was, of course, also under6tood that the subject should keep his mind a blank as much as it was in his power, and, at any rate, that he should not beforehand make up his mind what to do. The subjects, I must add, were perfectly trustworthy peoplecoworkers in the Psychological Laboratory.

        Now, while the screen was removed I at the same time loudly suggested some actionsuch as "Read!" "Write!" "Cut!" "Strike!" "Ring!" etc. On the table were objects appropriate to such actionsa book, a pen, a knife, a hammer, a bell. The subjects very frequently carried out the commands, the suggestions given to them.

        Of five hundred experiments made, about one half succeeded; that is, the subject carried out the suggestion given to him during the removal of the screen. Allowing ten per cent for chance, there remains about forty per cent in favour of suggestibility.

        On interrogating the subjects of their state of mind at the moment of action, many of them told me that they felt no desire nor any particular impulse to carry out the act suggested, but that they complied with my order out of sheer politeness. (I should say, though, that the fact of the order being realized so many times, be it even from mere politeness, indicates the presence of suggestibility.)

        Some of the subjects became totally unfitted to do anything at all. It seemed as if all activity was for the time being under some powerful inhibition.

        In the case of one subjectMr. S., one of the ablest men in the Psychological LaboratoryI found that my order was carried out in a reflex way; so much so that a few times, when I called out "Strike!" " Hammer!" the hand went down on the table instantaneously and with such violence that the table was nearly shattered. Mr. S. felt pain in his hand for some minutes. On one occasion I called out, "Look there!" Quick as lightning Mr. S. turned round and looked hard. On another occasion I commanded, "Rise!" Back moved the chair and up went Mr. S.

        Now this set of experiments, if regarded alone, certainly does not carry conviction as to the presence of suggestibility in all perfectly normal and healthy persons; but along with other experimentswith those that relate to suggestion of ideas, and with those in relation to choice suggestion, of which I shall soon give a detailed accountthis last set of movements' and acts' suggestion certainly contributes its mite of evidence. It is not, however, on account of their positive side that I value these movement experiments, but on account of their negative side. I shall resume this subject further on in its proper place. Interesting as that last line of investigation was, I still had to abandon it, because the experiments could not possibly be expressed in precise quantitative terms. Except in the case of Mr. S., I could not precisely know how far the experiment succeeded and how far it failed. The different factors remained unanalyzed, and the whole mechanism was extremely crude and primitive. Thanks to the advice of Prof. H. Münsterberg, I was enabled to continue my research further and penetrate deeper into one of the most obscure, most mysterious, but also most promising regions of human nature. The experiments which I am about to describe were carried out with great care and minuteness of detail. The new factors studied were carefully analyzed and separated. I must confess that at first I did not fully realize the import and value of these experiments; I saw in them nothing else than a further test and affirmation of the fact of normal suggestibility, especially on its efferent or motor side. The highest I thought of their value was that along with the preceding experiments they would carry to the mind convictionperfect certitude as to the universality of normal suggestibility. But later on, when I summed up the results and thought the matter over, I was glad to discover that the results had a profounder meaning than the one I put on them; that they pointed to something beyond, to something deeper and wider than the problem they were intended to solve.

        To pass now to the experiments themselves. The experiments were carried on in the following way: Six small squares (30 X 30 mm.) of different colours were placed on a white background. The white background with the six squares on it was again covered by a black carboard. The subject was told to fix his attention on the black cardboard for five seconds (time being measured by the metronome). At the end of five seconds the black cover was removed, and the subject had immediately to take one of the coloured squares, whichever he liked.

        The subjects were nineteen in number. No subject was allowed to take part in these experiments more than one hour a week. Precautions were also taken that the same series of colours should not be repeated in the experiments with the same subject. For this purpose Bradley's colours were used, which give an endless combination of different colours. At the beginning of each week the colours were rearranged in new series of six squares each; no series containing the same colour, the squares were all of different colours. Precaution was also taken to hide the arrangement of the experiments from the suhjects.4

        In these experiments on suggestion of choice the following six factors were studied:

        1. Abnormal position.

        2. Colored cover.

        3. Strange shape.

        4. Colour verbally suggested.

        5. Place verbally suggested.

        6. Environment.

        1. ABNORMAL POSITION.One of the coloured squares was placed in some abnormal way, thus:

        2. COLOURED COVER.Instead of the usual black cover a coloured cover was used in these experiments. A square of the same colour as that of the cover was placed in the series of squares.

        3. STRANGE SHAPE.One of the coloured squares was here of some peculiar shape, of the form of a triangle, oblong rectangle, rhomboid, pentagon, star, etc., thus


        4. COLOUR VERBALLY SUGGESTED.One of the coloured squares was shown to the subject, who had to determine its colour. This was not an easy task, as the subject had to tell the constituents of the colour, and give the precise name of it. The subject usually kept the coloured square in his hand, and spoke about it for more than a minute. In ease he did not succeed, I told him the name of the colour. Then the square was replaced in the series, and the experiment proper began.

        5. PLACE VERBALLY SUGGESTED.The place of one of the coloured squares was suggested by calling out a number during the removal of the cover and the set of choice, as, for instance, "Three!" meaning the third in the row beginning from the left hand. In order that the subject should understand the number suggested and get used to this mode of counting, I asked of him in other suggestion experiments that, after having chosen a coloured square, he should also tell its place, counting from left to right.

        6. ENVIRONMENT.One of the six coloured squares was put on a larger square of differently coloured paper. A fringe environing the square was thus formed:

        Special care was taken not to leave in the same place the square suggested, but to shift it with each subsequent experiment. The differently coloured squares suggested were each time put in different places, so that the subject should not form a habit of choosing from one place more than from another.

        To counteract all expectation as to what the nature of the experiment was, the experiments were constantly changed as to the nature of the factor, and, to be the more sure of completely eliminating expectation, sham experiments were introduced. Instead of the usual coloured squares, the subject frequently found a row of black squares, looking like a funeral march. These black squares were often screened by a cover of gay colour.

        Before I proceed to give a detailed account of the experiments, I think it would be well to give the precise meaning in which I here employ the terms of mediate and immediate suggestion and suggestibility.

        By immediate suggestion I mean to indicate the full realization of the suggestion given to the subjectthe fact of his taking the square suggested to him in a direct or indirect way.

By mediate suggestion I mean to indicate the fact of incomplete realization of the suggestionthe fact of taking a square next to the one suggested by the experimente.g.:

        d, Immediate suggestion.

        c or e, Mediate suggestion.

        The results are as follows:5


Per cent.
Immediate suggestion.... 47.85
Mediate suggestion........ 5.37
    Total suggestion......... 53.22



Immediate suggestion.... 38.16
Mediate suggestion........ 5.83
    Total suggestion......... 43.99



Immediate suggestion.... 43
Mediate suggestion........ 13
    Total suggestion......... 56



Immediate suggestion.... 28.89
Mediate suggestion........ 4.44
    Total suggestion......... 33.33



Immediate suggestion.... 19.41
Mediate suggestion........ 0.58
    Total suggestion......... 19.99



Immediate suggestion.... 30.44
Mediate suggestion........ 22.22
    Total suggestion......... 52.66


        Making now a table of the factors and arranging in the order suggestibility effected, we have the following:



Per cent.
Abnormal position................ 47.8
Strange shape...................... 43.0
Coloured cover..................... 38.1
Environment.......................... 30.4
Colour verbally suggested... 28.8
Place verbally suggested.... 19.4


        Mediate suggestibility necessitates a rearrangement of the factors:



Per cent.
Environment.......................... 22.2
Strange shape...................... 13.0
Coloured cover..................... 5.8
Abnormal position................ 5.3
Colour verbally suggested... 4.4
Place verbally suggested.... 0.5


        A scrutiny of the table of immediate suggestibility shows that the factors of abnormal position and of abnormal or strange shape give the strongest suggestion. A familiar thing in a strange abnormal position or shape produces the most effective suggestion. Nothing speaks so much to the childish or popular mind as a caricature, monstrosity, a grotesque figure. A distorted picture of a familiar scene or person will at once attract the attention of the child, and powerfully affect its conduct in case the picture is intended to show the fate of bad children. The angelical happiness of saints, the pure, holy bliss of martyrs, the intolerable torments suffered by the wicked in hell, speak volumes to the vulgar religious mind. When Vladimir, the Russian Kniase (king), intended to abandon paganism and accept a monotheistic religion, missionaries came to him from the Jews, Mohammedans, and Christians. No argument could affect the barbarian. The cunning Greeks then showed him a picture representing the day of judgment. The righteous enjoy eternal bliss in the company of beautiful maiden-like angels, while the wicked, with distorted faces, writhe and wriggle in agonies of pain. The infidels are cooked in enormous kettles containing a hellish soup of hot, seething oil and bubbling sulphur and pitch. The sinners, the blasphemers, are mercilessly fried and roasted by horned, tailed, cloven-hoofed, grinning, hideous-looking devils. Vladimir was deeply affected by the picture of the Christian hell, and at once accepted the Greek faith. This Russian tradition may serve as a good illustration of the great power of suggestion possessed by the two factors of abnormal position and strange shape.

        Turning now to the table of mediate suggestibility, we find that the factor of environment gives us as high a rate as 22.2 per cent, almost twice the rate of the mediate suggestibility possessed by the factor of strange shape, and more than five times the rate of the mediate suggestibility possessed by the factor colour verbally suggested. This can possibly be explained by the fact that one of the conditions of the environment factor was to put one of the squares on a differently coloured background. The fringed square looked somewhat prettier than its fellows, and it was this prettiness that enhanced the mediate suggestibility. An adorned, beautiful object sheds glory on its homely neighbors and makes them more eligible.

But however the case may be with the relative suggestibility of the particular factors studied, these last experiments on choice suggestion, together with the other suggestion experiments, establish the fact of normal suggestibility on a firm and unshakable basis. MAN IS A SUGGESTIBLE ANIMAL, par excellence.


1.  Zeitschrift, Januar, 1894.
2.  November and December, 1892.
3.  Let me add here that the figures bring out rather the relative than the absolute suggestiveness of the factors studied.
4   As the squares were rather small in size they could with equal facility be reached with either hand and there was, therefore, no tendency to prefer the squares of one side more than those of the other side. Besides, control-experiments with black squares were made by me; and these experiments still further confirmed the view that this factor of preference was totally absent.
5.  See Appendix A.


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