November 23, 1888.] 



SCIENCE. 



245 



the moon high up in the sky as really smaller than when near the 

 horizon, presents a case of such deception. 



No better instances of deceptions depending upon unusual objec- 

 tive arrangements can be found than the ordinary conjuring tricks. 

 Here deception depends solely upon an ignorance of the devices 

 •employed. When ink is turned into water, when two half-dollars 

 are rolled into one, when a box in which you have just placed an 

 article is opened and found to be empty, or when a card suddenly 

 changes from one face to another, deception takes place when the 

 spectator is ignorant that a chemical can change the color of liquids, 

 that one half-dollar is hollow and allows the other to fit into it, that 

 the box has a double bottom, and the card a flap, that, falling down, 

 shows another aspect. These objective arrangements are often 

 much more complex, and the conditions that ordinarily lead to cor- 

 rect inferences are imitated with remarkable ingenuity. The ac- 

 cepted rule of conjuring, to always first actually do that which after- 

 wards you desire the audience to believe you have done, shows keen 

 dnsight into the workings of the mind. When coins are caught in 

 the air and thrown into a hat, a few are really thrown in ; the others 

 palmed in the hand holding the hat, and allowed to fall when the 

 •other hand makes the appropriate motions. 



Leaving the objective conditions of deception, and turning to the 

 subjective, the psychological interest is deepened. If our condition 

 departs from the normal, however slightly, and we fail to recognize 

 the variation, illusion is apt to arise. The phenomena of contrast 

 and fatigue are simple cases in point. Fatigue the eye for red, and 

 it sees white light as green. Plunge the hand from hot water into 

 luke-warm water, and it will feel the latter as cold. When a dis- 

 turbed mental judgment is present to misinterpret such unusual 

 sensations, illusions of a very serious type may arise. But even 

 within the limits of normal judging powers, the emotions, the in- 

 terest, expectation, can alter the nature of a sense impression. In 

 all perception two factors contribute to the result, — the attitude of 

 the percipient, and the nature of the object perceived. When the 

 naturalist observes what the stroller overlooks, or the sailor detects 

 a distant sail when the landsman's eye sees nothing, it is because 

 the former knows what to expect. When expecting a friend, any 

 indistinct noise is converted into the rumbling of carriage-wheels, 

 as the mother hears in every sound the cry of her sick child. The 

 conjurer, taking advantage of this, creates an interest in some in- 

 significant detail, and draws the attention away from the real trick. 

 His wand, his motions, his talk, are all intended to give him a favor- 

 able moment for doing the real trick before theunobserving eyes of 

 the spectators. When he counts ' one, two, three,' centring all the 

 emphasis upon ' three,' and thus focusing the attention of the audi- 

 ence upon that instant, he does the real transformation at the un- 

 attended ' one ' or ' two.' The conjurer's art is largely composed of 

 devices for misleading the attention : a trick is successful accord- 

 ing to the setting that the performer can give to it. 



In one point, however, the conjurer's performance fails to illus- 

 trate the psychology of deception. The attitude of the spectator is 

 too definite. He knows that he is being deceived and has nothing 

 at stake. Quite different was it when such a performance carried 

 with it a belief in the magical and mystical, when the spectator 

 believed himself in the presence of powers that could be turned 

 against him and his welfare. The best parallel to this attitude in 

 modern times is seen in the physical phenomena of Spiritualism. 

 The medium performs to sitters in doubt as to the true explanation 

 of the phenomena, or more or less ready to credit every thing to the 

 supernatural. Such an expectation can see a miracle in the sim- 

 plest conjuring tricks ; and more than once have professional con- 

 jurers been declared to be mediums in spite of all protests from 

 themselves. The general rule at the seance, where the emotions 

 are strung to the highest pitch, and the judging faculties labor 

 under the worst conditions, is that the spectators see whatever they 

 are interested in seeing. The same form is recognized by various 

 spectators as the spiritual counterparts of totally dissimilar persons. 

 Only let the form be vague, the light dim, the emotions at a strain, 

 and what is lacking in the object will be supplied by the imagination 

 of the spectator. In the same phenomena each finds proof of his 

 own pet beliefs, until the refusal to mistrust the evidences of an ex- 

 cited consciousness leads to actual mental disorder. The records 

 of the witchcraft delusion show the same result : the facts are seen 



in the light of the prevailing theory. " With the doctrines of mod- 

 ern Spiritualism to be supported, the number of mediums and mani- 

 festations will be correspondingly abundant. Create a belief in the 

 theory, and the facts will create themselves." 



To all this must be added the enormous influence of mental con- 

 tagion. Wherever a subjective influence contributes to the result- 

 ing deception, contagion plays a part, — fear, panic, fanaticism, 

 superstition, all flourish in crowds. The witchcraft delusion and 

 the spiritualistic movement show to what dimensions psychic be- 

 liefs can attain when fanned by the flames of emotional enthusiasm. 

 If, in addition to all this in which self-deception plays the leading 

 role, we add the variety of illusions carried on by conscious fraud, 

 we may perhaps appreciate the enormity of error through which 

 civilization has made its way. Such errors are destroyed, not by 

 logical disproof, but by rendering unsuitable the soil upon which 

 they flourish. 



The Alleged Evolution of Color Sensitivity.' — To 

 test the theory frequently met with, that in the thirty centuries 

 of civilization the human retina has developed a gradually in- 

 creasing color perception, — the homeric man seeing chiefly the red 

 end of the spectrum, and blue coming in much later, — M. G. 

 Pouchet compared the proportion of color epithets in types of the 

 literature of various ages. He selected (i) a very recent work of 

 M. Guy de Maupassant on water, (2) ' Paul et Virginie,' as typical 

 of the beginning of the century, (3) Books I. and VII. of ' Tele- 

 maque ' for the same reason, (4) Chapters XIV. to XXII. of the 

 second book of ' Pantagruel,' taken at random from ' Rabelais,' and 

 (5) a short romance, ' I'Ane,' attributed to Lucian. (i) gave the 

 following number of color appellations : white, 21 times ; black, 14 ; 

 gray, 3 ; brown, 4; all kinds of reds, 23 (including pure red — 15) ; 

 yellow, 5 ; green, 6 ; varieties of blue, 17 (in which pure blue occurs 

 12 times); and violet, 3 times; in all, 96 terms. Taking only the 

 primary colors, we have red, 26 ; blue, 17 ; green, 6 ; yellow, 5 ; and 

 violet, 3. (2), though more extended a work than (i), gave the 

 following : white, 1 3 ; black, 1 5 ; gray, i ; varieties of red, 1 1 ; vari- 

 eties of blue, 7 ; of green, 8 ; yellow, I : or red, 1 1 ; green, 8 ; blue, 

 7; yellow, I. (3) gives black, 2; white, 2; red and shades, 4; 

 green, 2. One might add golden, 2, and reddening, 2 ; and would 

 thus have red, 6 ; yellow, 2 ; green, 2. (4) gives black, i ; white, 3 ; 

 red and varieties, 7 ; green, 2 ; blue, i. (5) gives but one name, red. 

 The result is that writers show a marked tendency to describe red 

 things, and this tendency holds good for all times. If we survey 

 the ordinary color impressions to which the retina is exposed, we 

 find, first, a general brightness involving all colors, — the blue of 

 the sky, the reds of sunrise and sunset, the whites and grays of 

 clouds ; words expressive of these abound. Considering next 

 colors in which whiteness does not enter, we find that a true violet 

 is extremely rare in nature. Blue, too, is little fitted to be physio- 

 logically conspicuous as it presents itself in nature. Yellow is more 

 extended, especially on flowers, but it loses its individuality in agen- 

 eral whiteness. There remain green and red. The reason why 

 red has acquired so striking an effect is, that, owing to the prepon- 

 derance of green, the red is conspicuous by contrast. Again, red, 

 as the color of blood, as the symbol of fire, as the color first and 

 most sought after in dyes, would soon acquire a moral and intel- 

 lectual prominence that would lead to its frequent mention. The 

 proper conclusion, then, is not that our ancestors were unable to see 

 blue and its allied shades, but that they followed the natural ten- 

 dency to describe what was prominent, and this coincides with the red. 

 The Mental Powers of the Ape. — According to a recent 

 letter to the London Times, Mr. Romanes has succeeded in teach- 

 ing an ape to count ; not merely to detect differences of number, 

 but to associate different groups of sensations with vocal sounds. 

 Fearing that if too complex the experiment would entirely fail, the 

 counting was attenipted only up to five. By refusing all but the 

 number of straws asked for, and rewarding the ape for a correct 

 performance, the creature was taught to give at command one, two, 

 three, four, or five straws. His method is to take the straws one 

 by one into his mouth, until one less than the required number have 

 been collected ; then, taking up an additional straw, he hands it over, 

 together with those in his mouth, — certainly a remarkable perform- 

 ance. 



^ Revue Scientifique, Oct. 13. 



