The saying that appearances are deceptive is an inheritance from ancient times; to Oriental and to Greek philosophers the illusory nature of the knowledge furnished by the senses was a frequent and a fertile theme of contemplation and discussion. The same problem stands open to the psychologist of to-day; but, profiting by the specialization of learning and the advance of technical science, he can give it a more comprehensive as well as a more practical answer. The physiological activities underlying sense-perception are now fairly well understood; the experimental method has extended its domain over the field of mental phenomena; and in many ways have we become more expert in addressing our queries to the sphinx, Nature, so as to force a reply. To outline the position of modern psychology with reference to this interesting problem of deception is the object of the present essay.

I

In a sense-impression we recognize a primitive element in the acquisition of knowledge. The deprivation of a sense even under most favorable circumstances leaves some traces of an incomplete mental development. This is due, not to the mere sense-impressions that the organ furnishes, but to the perception and coÖrdination of these by inferential processes of a more complex nature. It is not the eye of the eagle, but the brain directing the human eye, that leads to intellectual supremacy. Physiology recognizes this distinction as one between lower and higher brain-centres. A man may have his retina or his optic nerve injured, and so be blind in the ordinary sense of the word. He is prevented from acquiring further knowledge by this avenue; but, unless he become blind in early childhood, he will retain a memory for visual images, will be able more or less clearly to imagine pictorially the appearances of objects from verbal descriptions, and in the free roamings of his dream fancy will live in a world in which blindness is unknown. On the other hand, there is a condition resulting from the disintegration of certain portions of the finely organized cortex of the brain, in which the patient may retain full sight and understanding, but be unable to derive any meaning from what he sees. The same cluster of sensations that enables us to recognize a book, a picture, a face, and to arouse all the numerous associations attaching to these, is as unmeaning to him as the symbols of a cipher alphabet. This condition is termed "psychic blindness;" and what is there lost is not the power of vision, but of interpreting, of assimilating, of reading the meaning of visual sense-impressions. It is this interpreting and assimilating process that is largely concerned in the formation of illusions.

In the experiences of daily life we have to do not with simple sensations, but with more or less complex inferences from them; and it is just because these inferences go on so constantly and so unconsciously that they are continually and persistently overlooked. It is an occasional experience in raising a water-pitcher to have the vessel fly up in the hand in a very startling manner,—the reason for this being that the pitcher, which one is accustomed to find well filled, happens to be empty. This experience shows that we unconsciously estimate the force necessary to raise the vessel, but only become conscious of this train of inference when it happens to lead to conclusions contradictory of the fact. The perception of distance, once thought to be as primitive a factor in cognition as the impression of a color, is likewise the result of complex though unrealized inferences; and the phenomena of the stereoscope, by imitating the conditions of the perception of solidity and thus making us see as solid the flat representations of a pair of diagrams or photographs, furnish a brilliant illustration of the variety and complexity of such unconscious reasonings. As for essential purposes normal persons have a common anatomy, a common physiology, and a common psychology, it results that we draw these unconscious inferences after the same pattern; and so completely are they the outcome of the normal reactions to our common environment, that we need not be, and as a rule are not, aware of their existence until—and probably with some little effort—our attention is directed to them. Unconsciously and spontaneously we learn to see,—that is, to extract meaning out of the sense-impressions that fall upon the retina.

The simplest type of a deception occurs when an inference or an interpretation of this type, owing to an unusual disposition of external circumstances, leads to a conclusion which other and presumably superior testimony shows to be false. Thus, in the observation which Aristotle knew and described, that a pea or other round object held between two fingers crossed one over the other seems double, it is the unusual position of the fingers that induces the illusion. Under ordinary circumstances a sensation of contact on the left side of one finger and on the right side of the finger next to it (to the right) could only be produced by the simultaneous application of two bodies. We unconsciously and naturally make the same inference when the fingers are crossed, and thus fall into error—an error, it is important to observe, which we do not outgrow but antagonize by more convincing evidence. The pea held between the crossed fingers continues to feel like two peas, but we are under no temptation to believe that there really are two peas.

The limitations of our senses lead directly to the possibilities of their deception, which may in turn be realized inadvertently or utilized intentionally. We appreciate how defective is our localization of sound when we attempt to find a cricket by locating whence proceeds its chirp; the same difficulty lends uncertainty to the determination of the direction of fog-horn signals of passing steamers. This uncertainty coÖperates in the illusions of ventriloquism; it is involved in the smack which one clown gives another, but which is really the clapping of the hands of the supposed victim; it produces a realistic effect when a cannon is fired on the stage, for it is necessary only to show the flash while the noise is produced behind the scenes. Again, the stimulation of the retina is ordinarily due to the impinging upon it of light-waves emanating from an external object. Accordingly, when the retina is disturbed by any exceptional cause, such as a blow on the head or an electric shock to the optic nerve, we have a sensation of light projected outward into space. The perception of our own locomotion, which is likewise a highly inferential process, offers illustrations of casual illusion and of artificial deception. When on a train, it is by the passing-by before our eyes in the opposite direction of trees and posts and other features of the landscape, that we realize that we are moving forward; accordingly, when a train alongside moves out before our own train has started, we have a distinct realization that we are moving backwards so long as we look at the forward-moving train. There is an illusion devised for amusement called the "Magic Swing," in which one is apparently swung to and fro with wider and wider excursions until a complete revolution is apparently made from a vertical to a horizontal, through the antipodal position, back to the horizontal and the normal. In reality, only a slight motion is imparted to the swing, but the inclosing walls, which are painted to represent a forest scene, are themselves revolved forward and then backward about the axis from which the swing is suspended. As, however, we have no experience with oscillating trees, we unconsciously infer the oscillations to be and feel them in our own persons. In another application of the same illusion we seem to be let down into the bowels of the earth; but after a slight actual descent the car remains stationary while the illuminated sides of the shaft, which are suitably painted, are moved panorama-like in an upward direction. In brief, we are creatures of the average; we are adjusted for the most probable event; our organism has acquired the habits impressed upon it by the most frequent experiences; and this has induced an inherent logical necessity to interpret a new experience by the old, an unfamiliar by the familiar. In describing illusions of the above type, Mr. Sully aptly says that they "depend on the general mental law that when we have to do with the unfrequent, the unimportant, and therefore unattended to, and the exceptional, we employ the ordinary, the familiar, and the well known as our standard." Illusion arises when the rule thus applied fails to hold; and whether or not we become cognizant of the illusion depends upon the ease with which the exceptional character of the particular instance can be recognized, or the inference to which it leads be opposed by presumably more reliable evidence.

II

To make things seem more wonderful than they are, to possess knowledge and exhibit power beyond the ken of the multitude, has exercised a fascination upon the human mind in all its stages of development. The primitive conjuring of the ancient priest or of the savage medicine-man, the long tradition of Oriental legerdemain, and the stage performances of the modern prestidigitateur are all connected with deep-seated human instincts. It has even been suggested[3] that the mimicry and death-feigning instincts of animals, though essentially biological in type, are yet related to the psychological instincts of deception which make their first clear appearance in the higher animals and assume a distinctive position in the psychological equipment of childhood. The conjuring tricks or paradoxes which apparently contradict or rise superior to ordinary experience, furnish the most various types of illustration of the psychology of deception. Whether presented as miracle by priest or by thaumaturgist or by expounder of the black art, or presented as proof of spirit agency by the modern spiritualistic medium or his less pretentious predecessors, or by the stage performer for entertainment, the analysis of what was actually done, and the accounts of what the spectators saw or believed that they saw, illuminate with striking brilliancy the modus operandi of the processes whereby appearance takes the semblance of reality and observation is shrewdly led astray. The conjurer thus becomes a suggester and an actor, not a mere exhibitor of his manipulative skill.

As our present purpose is to investigate the nature of real deception, of the formation of false beliefs which may in turn lead to unwise action, it will be well to note that even such elementary forms of sense-deceptions as those just noted may fall under this head. No one allowed the use of his eyes will ever believe that the pea held between the crossed fingers is really double, but children often think that a spoon half immersed in water is really bent. Primitive peoples believe that the moon really grows smaller as it rises above the horizon; and the ancients could count sufficiently upon the ignorance of the people, to make use of mirrors and other stage devices for revealing the power of the gods. The ability to correct such errors depends solely upon the possession of certain knowledge or of a confidence in its existence.

Continuing with deceptions dependent upon exceptional external arrangements, we may find in conjuring tricks simple and complex illustrations in great perfection. When wine is turned into water, when two half-dollars are rolled into one, when a box into which an article has just been placed is immediately opened and found to be empty, when a handkerchief is torn and made whole again, when the performer drives a nail through his finger, when a coin suddenly appears out of space at the end of a wand, when a card which you have just assured yourself is the ace of hearts on second view is the king of spades, when a bowl filled with water in which goldfish are swimming is produced from under a handkerchief, when a child rests horizontally in mid-air supported only on one elbow,—you are misled or mystified or deceived in so far as you are unaware that the wine was potassium permanganate and sulphuric acid, and was clarified by sodium hyposulphite; that the one half-dollar is hollow and the solid one fits into it; that the box has a double bottom controlled by a secret spring; that the real handkerchief was not torn but another substituted for it; that the nail has been replaced by one that fits around the finger; that the wand is hollow, and a spring controls the appearance or withdrawal of a split coin at its other end; that one half of the card is printed on a flap which, by falling down, shows another aspect; that the bowl covered with a rubber cap was secreted under the coat of the performer; that the child wears a steel suit fitted with joints that lock and become rigid. All these are technical devices which amuse us by the ingenuity of their construction, and, though they may be most baffling, provoke about the same type of mental interest as does a puzzle or an automaton. Ignorance of this technical knowledge or lack of confidence in its existence may convert these devices into real deceptions by changing the mental attitude of the spectator. However, the plausibility of such performances depends so much upon their general presentation that they seldom rely for their effectiveness solely upon the objective appearances presented. They are given a dramatic setting, or put forward as examples of newly discovered forces or of magical control; and this makes them far more effective than this bare account would suggest.

Asking the reader, then, to bear in mind the very great number and ingenuity of such devices, and insisting once more that the only complete safeguard against being misled by them to the extent of forming false conceptions of their modus operandi, is the acquisition of the purely technical knowledge that underlies their success, I shall cite in detail a trick combining illustrations of several of the principles to be discussed. Several rings are collected from the audience upon the performer's wand; he takes the rings back to the stage and throws them upon a platter; a pistol is needed, and is handed to the performer from behind the scenes; with conspicuous indifference he hammers the precious trinkets until they fit into the pistol. A chest is hanging on a nail at the side of the stage; the pistol is fired at this chest, which is thereupon taken down and placed upon a table towards the rear of the stage. The chest is unlocked and found to contain a second chest; this is unlocked and contains a third this a fourth. As the chests emerge they are placed upon the table; and now from the fourth chest there comes a fifth, which the performer carries to the front of the stage and shows to contain bonbons around each of which is tied one of the rings taken from the audience. The effect is most startling. This is the appearance of the trick from the audience. Now let us consider what really takes place. In the hand holding the wand are as many brass rings as are to be collected. In walking back to the stage the genuine rings are allowed to slip off the wand and the false rings to take their places. This excites no suspicion, as the walking back to the stage is obviously necessary, and never impresses one as part of the performance. The pistol is not ready upon the stage, but must be gone for; and as the assistant hands the performer the pistol, the latter transfers to the assistant the true rings. The hammering of the false rings is now deliberately undertaken, thus giving the assistant ample time to tie the true rings to the bonbons; and, while all attention is concentrated upon the firing of the pistol, the assistant unobtrusively pushes a small table on to the rear of the stage. This table has a small fringe hanging about it, certainly an insignificant detail, but none the less worth noting. The chests are now opened, and, after having shown the audience that the second chest comes out of the first, the third out of the second, and so on, the performer can very readily and quickly draw the last, smallest chest from a groove under the table, where it was concealed by the aforesaid fringe, and bring it forward as though it had come out of the next larger chest; this smallest chest is opened and the trick is accomplished. So thoroughly convinced is the observer by the correctness of his first three inferences that the last box came out of the one before it, that I venture to say this explanation does not occur to one person in many thousand, and that most of the audience would have been willing to affirm on oath that they saw the last box so emerge. The psychology of the process, then, consists in inducing the spectator to draw the natural inference, which, in this case, it has been carefully arranged shall be a wrong one.

Deception becomes real according to the skill with which the conditions of reality are imitated. The dexterity and training of the professional conjurer are measured by the fidelity with which he mimics the movements which are supposed to be done. The life-likeness of the movement with which the late Hermann could take up an imaginary orange with both hands from a table (the orange was really let down in a trap on the table as the hands were placed over it), and carry it over to another table where it mysteriously disappeared or passed through a hat, was quite irresistible. Equally so was his palming, or his production of objects from his person, or out of the air, or in out-of-the-way places. The mimetic movements accompanying these actions were so vividly realistic, the misdirection of the attention was so perfect, as to produce a complete hallucination of the appearance of objects from places from which they never emerged. When this was preceded by an actual sleight-of-hand movement, a true hallucination resulted; for example, in the trick of the flying cards which were skilfully thrown to all parts of the auditorium, a card was occasionally thrown which seemed to disappear mysteriously in mid-air; but in reality no card had been thrown but only the movements of throwing it imitated. A rabbit was tossed up in the air two or three times, and then disappeared at the report of a pistol; in reality the rabbit was not tossed at all on the last apparent throw, but was slipped into the hollow of the table.[4]

The more closely the conditions that lead to correct inferences in ordinary experiences are imitated, the more successful will be the illusion; and a useful principle of conjuring illusions is to first actually do that which you afterward wish the audience to believe that you continue to do. Thus, when coins are caught in mid-air and thrown into a hat, a few are really thrown in; but the others are palmed in the hand holding the hat, and allowed to fall when the other hand makes the appropriate movements. Some of the rings to be mysteriously linked together are given to the audience for examination and found to contain no opening, the audience at once concluding that the rings which the performer retains are precisely like them. In general, to gain the confidence of the person to be deceived is the first step alike in sleight-of-hand and in criminal fraud.

III

As we turn from the objective to the subjective conditions of deception, we enter the true domain of psychology; for the most scientific deceiver is he who employs least external aids, and counts most upon his power of captivating the intellect. Just as we interpret appearances by the forms they most commonly assume, so it is our average normal selves that interpret them. A variation in our sense-organs or in our judging powers will lead to illusion. The effects of contrast may serve as apt illustrations. When passing from a dark to a light room the light seems glaringly bright; a hand immersed in hot water and then in lukewarm water will feel the latter as cold; when accustomed to the silence of the country the bustle of the city seems unusually noisy. Fatigue produces similar results. Fatigue the eye for red, and it sees white light as green; the last mile of a long walk seems the longest; the last hour of a long wait, the most tedious. So long as we recognize our unusual condition and allow for its effects, we are not deceived; but under the influence of emotion this power is readily lost, as it may be permanently lost in the insane. The delusions of the insane are often influenced by misinterpretations of real but abnormal sensations under the guidance of a dominant idea. On the basis of an anÆsthetic skin a patient may come to believe that he is made of glass or stone; subjective noises in the ear, due to disturbances of the circulation, are transformed into the jeers and taunts of an invisible persecutor. But for the present we will assume that the judging powers do not vary beyond their normal limits.

In every perception two factors contribute to the result. The one is the nature of the object perceived, the other that of the percipient. The effect of the first factor is obvious and well recognized; the importance of the second factor is more apt to be overlooked. The sunset is a different experience to the artist from what it is to the farmer; a piece of rocky scenery is viewed with quite a different interest by the artist and the geologist. The things that were attractive in childhood have lost their charm; and what was then, if noticed at all, considered stupid, has become a cherished hobby. Even from day to day, our interests change with our moods, and our views of things brighten with the weather or the good behavior of our digestive organs. Not only will the nature of the impression change with the interests of the observer, but even more, whether or not an object will be perceived at all, will depend upon the same cause. The naturalist sees what the stroller entirely overlooks; the sailor detects a ship in the distant horizon where the landsman sees nothing; and this is not because the naturalist and the sailor have keener vision, but because they know what to look for. Whenever an impression is vague, or an observation made under poor conditions, this subjective element comes to the front. Darkness, fear, any strong emotion, any difficulty in perception reveal the same influence. "La nuit tous les chats sont gris." Expectation, or expectant attention, is doubtless the most influential of all such factors. When awaiting a friend, any indistinct noise is readily converted into the rumbling of carriage-wheels; the mother hears in every sound the cry of her sick child. After viewing an object through a magnifying-glass, we detect details with the naked eye which escaped our vision before. In spite of the fact that the answer in the book happens to be wrong, a considerable proportion of the class succeeds in reaching it. Everywhere we are apt to perceive what we expect to perceive, in the perception of which we have an interest. The process that we term "sensation," the gathering of evidence by the senses, is dual in character, and depends upon the eyes that see as well as upon the things that are present to be seen.

Accordingly, the conjurer succeeds in his deception by creating an interest in some unimportant detail, while he is performing the real trick before our eyes without our noticing it. He looks intently at his extended right hand, involuntarily carrying our eyes to the same spot while he is doing the trick with the unobserved left hand. The conjurer's wand is extremely serviceable in directing the spectator's attention to the place where the performer desires to have it.[5] A call upon the attention in one direction prevents its dispersion in another. When engrossed in work, we are oblivious to the noise of the street or even to the knock at the door. An absent-minded person is one so entirely "present-minded" to one train of thought that other stimuli go unperceived. The pickpocket is psychologist enough to know that at the railway station, the theatre, or wherever one's attention is sharply focused in one direction, is he apt to find the psychological moment for the exercise of his pursuit. It is in the negative field of attention that deception effects its purpose. Houdin, the first of the famous prestidigitateurs (died 1871), gives it as one of his rules never to announce beforehand the nature of the effect which you intend to produce, in order that the spectator may not know where to fix his attention. He also tells us that whenever you count "one, two, three," as preliminary to the disappearance of an object, the real vanishing must take place before you say "three,"—for the audience have their attention fixed upon "three," and whatever is done at "one" or "two" entirely escapes their notice. The "patter" or setting of a trick often constitutes the real art of its execution, because it directs or rather misdirects the attention. When performing before the Arabs, Houdin produced an astounding effect by a very simple trick. Under ordinary circumstances the trick was announced as the changing of the weight of a chest, making it heavy or light at will. The mechanism was simply the attachment and disconnection of an electro-magnet, in those days a far less familiar affair than now. To impress the Arabs he announced that he could spirit a man's strength away and restore it again at a moment's notice. The trick succeeded as usual, but was changed from a mere trick to sorcery—the Arabs declaring him in league with the devil.

The trick, above cited, of supporting a child in mid-air, was performed by Houdin at the time when the inhalations of ether for purposes of insensibility were first introduced. This idea was in the minds of the audience, and magical effects were readily attributed to etherization. Accordingly the trick was announced as "suspension in equilibrium by atmospheric air through the action of concentrated ether," and so successfully was this aspect of the trick accepted that protests were sent in against "the unnatural father who sacrificed the health of his poor child to the pleasures of the public." In the same way, Kellar introduces a "thought-reading" performance, by going through the movements of hypnotizing the lady who assists in the trick; this enables him to present the phenomenon in a mysterious light, and incidentally his manipulations furnish the opportunity to connect the end of a speaking-tube concealed in the lady's hair with another portion attached to the chair. In brief, the effect of a trick depends more upon the receptive attitude of the spectators than upon what is really done. "Conjuring," Mr. Triplett observes, "is thus seen to be a kind of game of preperception wherein the performer so plays upon the psychical processes of his audience that the issues are as he desires."

There is, too, a class of tricks which illustrate a process, the reverse of this; and which depend for their Éclat upon making the issues coincide with the apparently freely expressed choice of the spectator, while really the performer as rigidly determines the result as in all other cases. One of the best of these proceeds by collecting some eight or nine questions prepared by as many persons in the audience, then placing them in a hat, drawing out one at random, and finding the answer to the question thus selected written on the inside surfaces of a pair of slates. The deception begins in the substitution for the collected slips of paper, of the same number of slips all containing the same carefully prepared question; the production of the writing on the blank slate is a chemical technicality. It is a similar result that is obtained in forcing a card; or when the conjurer asks the audience to select one of a group of similar objects, and then himself decides whether the selected object shall be used for the trick or discarded; likewise, when a magic bottle is presented from which any desired variety of liquor may be produced, it is easy to suggest the choice according to the available possibilities. There is thus an imitation of the psychological factors as well as of the objective factors of real experience; and both are utilized in the deceptions of the professional conjurer.

The art of misleading the attention is recognized as the point of good conjuring, the analogy of the diplomacy that makes the object of language to conceal thought; and many appropriate illustrations of this point may be derived from this field. The little flourishes, tossing an object up in the air, ruffling or springing a pack of cards, a little joke—all these create a favorable opportunity, a temp when the attention is diverted and the other hand can reach behind the table or into the "pocket." It is not necessary to pursue further these details of technique; it will suffice to analyze the points of interest in the chest-and-ring trick described above. Here the moment for the exchange of the rings is the one which is least suggestive of its being a part of the performance, and therefore least attended to. The preparations for the shooting absorb the attention and allow the introduction of the small table at the rear to pass unnoticed; while the series of drawings of the chests so entirely prepare the spectator for the appearance of the last chest from the one preceding, that he actually sees the chest emerge from where it never had been.

It is necessary, however, not only to provide an opportunity for non-attention or misdirected attention, but to be able to take advantage of it when the proper moment arrives. Here enters the dexterity alike of pickpocket and of conjurer. The training in quickness and accuracy of motion, in delicacy of touch, in the simultaneous perception of a wide range of sense-impressions, are among the psychological requisites of a successful conjurer. He must dissociate the natural factors of his habits, actually doing one thing while seemingly attending to another; at the same time his eyes and his gestures and his "patter" misdirect the attention to what is apparently the essential field of operation, but really only a blind to distract attention away from the true scene of action. The conjurer directs your attention to what he does not do; he does not do what he pretends to do; and to what he actually does he is careful neither to appear to direct his own attention nor to arouse yours.

IV

There is, however, one important factor lacking in the conjurer's performance to illustrate completely the psychology of deception; it is that the mental attitude of the observer is too definite. He knows that he is being deceived by skill and adroitness, and rather enjoys it the more, the more he is deceived. He has nothing at stake; his mind rests easy without any detailed or complete explanation of how it was done. Quite different must have been the feeling of the spectator before the necromancer of old, in whose performance was seen the evidence of secret powers that could at a moment's notice be turned against any one to take away good luck, to bring on disease, or even to transform one into a beast. When magic spells and wonder-working potions were believed in, what we would now speak of as a trick was surrounded with a halo of awe and mystery by the sympathetic attitude of the spectators. The most complete parallel to this in modern times is presented by the physical phenomena of Spiritualism; and so many of the manifestations presented by performing mediums in evidence of Spiritualism have been exposed and proven to be conjuring tricks, that it is no longer an assumption to consider them in this connection. Spiritualistic phenomena present a perfect mine for illustrations of the psychology of deception, and it is these that I shall consider as the final topic in this cursory view.

The first general principle to be borne in mind is that the medium performs to spectators in doubt as to the interpretation to be placed upon what they see, or more or less prepared or determined to see in everything the evidence of the supernatural. This mental attitude on the part of the spectators is worth more to the medium than any single factor in the performance. The difference between such a presentation and one addressed to persons cognizant of the conjuring element in the performance and interested in its detection, cannot be exaggerated. It is this that makes all the difference between the sÉance swarming with miracles, any one of which completely revolutionizes the principles of science, and the tedious dreariness of a blank sitting varied only by childish utterances and amateurish sleight-of-hand. Careful observers often report that the very same phenomena that were utterly beyond suspicion in the eyes of believers are to unprejudiced eyes so apparent "that there was really no need of any elaborate method of investigation"; close observation was all that was required, and Mr. Davey, who conducted an admirable investigation of the reliability of accounts of sleight-of-hand performances, has experimentally shown that of equally good observers, the one who is informed of the general modus operandi by which such a phenomenon as "slate-writing" is produced will make much less of a marvel of it than one who is left in doubt in this regard.

With these all-powerful magicians—an expected result and the willingness to credit a marvel—clearly in mind, let us proceed from those instances in which they have least effect up to the point where they form the chief factor. First come a host of conjuring tricks performed on the stage in slightly modified forms, but which are presented as "spiritualistic." So simple a trick as scratching a name on one's hand with a clean pen dipped in water, then writing the name on a slip of paper, burning the slip and rubbing the part with the ashes, thus causing the ashes to cling to the letters formed on the hand and reveal the name, has been offered as a proof of spirit agency. Whenever an article disappears or rapidly changes its place, the spiritualist is apt to see the workings of hidden spirits; and over and over again have the performances of professional conjurers been declared to be spiritual in origin in spite of all protest from the conjurers themselves. Here everything depends upon the possession of certain technical knowledge; judging without such knowledge is apt to be mere prejudice. Another very large class of phenomena consists of those in which the performer is placed in a position apparently inconsistent with his taking any active part in their production; rope-tying tests, cabinet sÉances, the appearance of a "spirit-hand" from behind a screen, locking the performer in a cage, sewing him in a bag, and so on. The psychologist has very little interest in these; their solution depends upon the skill with which knots may be picked, locks unfastened, and the other devices by which security may be simulated. The chief interest in such performances is the historical one, for these have done perhaps more than anything else to convince believers of the truth of Spiritualism. Here, where everything depends upon the security of the fastenings (for once free, the medium can produce messages from the spirit-land limited only by his ingenuity and boldness), upon the particular moment when the examination was permitted or the light turned down, upon the success with which an appearance of security and intactness of seals and knots may be simulated, it might be supposed that all possible precautions had been taken to control and eliminate these possibilities; while, as a matter of fact, the laxity of most investigators in this regard is well known. These performances deceive because people overlook the technical acquisitions needed to pronounce upon the possibility or impossibility of a fastening having been tampered with and apparently restored without detection. If manufacturers of safes were equally credulous, and gave equally little time to the study of the security of locks, "safe" would be an ironical expression indeed.

Passing next to the most interesting of spiritualistic manifestations, those in which self-deception comes to the foreground, I need hardly dwell at length upon the tilting of tables, the production of raps by movements of which the sitters are unconscious; for these have been so often and so ably presented that they must now be well understood. Suffice it to say that it has been objectively proven that it is almost impossible not to give some indication of one's thoughts, when put upon the strain; and that under excitement, these indications may become palpably plain and yet remain unperceived by the individual who gives them. The extreme subtlety of these indications is met by the unusual skill of the professional mind-reader, who takes his clue from indications which his subject is "absolutely confident he did not give." The assurances of sitters that they know they did not move the table are equally valueless; and nothing but objective tests will suffice. The most wholesome lesson to be derived from the study of these phenomena is the proof that not all our intentions and actions are under the control of consciousness, and that, under emotional or other excitement, the value of the testimony of consciousness is very much weakened. Again, it is almost impossible to realize the difficulty of accurately describing a phenomenon lying outside the common range of observation. Not alone that the knowledge necessary to pronounce such and such a phenomenon impossible of performance by conjuring methods is absent, but with due modesty and most sincere intentions the readiness with which the observing powers and the memory play one false is overlooked. In the investigation of Mr. Davey, above referred to, the sitters prepared accounts of the "slate-writing" manifestations they had witnessed, and described marvels that had not occurred, but which they were convinced they had seen—messages written on slates utterly inaccessible to Mr. Davey, and upon slates which they had noticed a moment before were clean. The witnesses are honest; how do these mistakes arise? Simply a detail omitted here, an event out of place there, an unconscious insertion in one place, an undue importance given to a certain point in another place—nothing of which any one needs feel ashamed, something which it requires unusual training and natural gifts to avoid. The mistake lies in not recognizing our liability to such error.

If, however, the spectator is once convinced that he has evidence of the supernatural, he soon sees it in every accident and incident of the performance. Not only that he overlooks natural physical explanations, but he is led to create marvels by the very ardor of his sincerity. At a materializing sÉance the believer recognizes a dear friend in a carelessly arranged drapery seen in a dim light. Conclusive evidence of the subjective character of such perceptions is furnished by the fact that the same appearance is frequently recognized by different sitters as the spiritual counterpart of entirely different and totally dissimilar persons. A "spirit-photograph" is declared to be the precise image of entirely unlike individuals. In the "Revelations of a Spirit Medium," we read that a wire gauze mask placed in front of a handkerchief, made luminous by phosphorus, and projected through the opening of the cabinet, was "recognized by dozens of persons as fathers, mothers, sisters, brothers, cousins, sweethearts, wives, husbands, and various other relatives and friends." Each one sees what he expects to see, what appeals to his interests the most intensely. What the unprejudiced observer recognizes as the flimsily disguised form of the medium, the believer transforms into the object of his thoughts and longings. Only let the form be vague enough, the light dim enough, the emotions upon a sufficient strain, and that part of perception in which the external image is deficient will be readily supplied by the subjective tendencies of each individual. In the presence of such a mental attitude the possibilities of deception are endless; the performer grows bolder as his victim passes from a watchful, critical attitude to one of easy conviction, and we get scientific proofs of the fourth dimension of space, of the possibility of matter passing through matter, of the levitation or elongation of the medium's body, of the transcendence of the laws of gravity. And the same performance that convinced Professor Zoellner of the reality of the fourth dimension of space would prove to the spiritualist the intercourse with deceased friends, would convince the theosophist of the flight of the performer's astral body; and, it may not be irrelevant to add, it was the same type of performance that served and yet serves to terrify the minds of uncultivated and superstitious savages. All depends not upon what is done, but upon the mental disposition of the spectator. Little by little, through neglect, through mal-observation and lapses of memory, through an unwillingness to mistrust the reports of an excited consciousness, caution is abandoned and credulity enters. Mediums are actually seen flying out of one window and in through another. The wildest and most far-fetched fantastic explanation is preferred above a simple one; the bounds of the normal are passed; real hallucinations set in; conduct becomes irrational, and a state hardly distinguishable from insanity ensues. If this seems improbable, turn to the records of witchcraft persecutions and read upon what trifling and wholly imaginary evidence thousands of innocent lives were sacrificed; and this not by ignorant, bloodthirsty men, but by earnest, eminent, and religious leaders. A child is taken sick, is remembered to have been fondled by an old woman; therefore the woman has put the child under a spell and must be burned. A man sees an old woman in the woods, and, on turning about, the old woman is gone and a hare flies across his track; he concludes that she turned herself into a hare, and the witch test is applied. When the personal devil was believed in, he was seen daily clothed in the garments that imagination had given him, and engaged in mischief and villainy of all kinds. When witchery was the dominant superstition, all things gave evidence of that. So long as Spiritualism forms a prominent cult with a real hold upon the beliefs of its adherents, the number of mediums and manifestations will be correspondingly abundant. Create a belief in the theory, and the facts will create themselves.

V

In the production of this state of mind a factor as yet unmentioned plays a leading rÔle, the power of mental contagion. Error, like truth, flourishes in crowds. At the hearth of sympathy each finds a home. The fanatical lead, the saner follow. When a person of nervous temperament, not strongly independent in thought and action, enters a spiritualistic circle, where he is constantly surrounded by confident believers, all eager to have him share their sacred visions and profound revelations, where the atmosphere is replete with miracles, and every chair and table may at any instant be transformed into a proof of the supernatural, is it strange that he soon becomes affected by the contagion of belief that surrounds him? He succumbs to its influence imperceptibly and hesitatingly at first, and perhaps yet restorable to his former modes of thought by the fresh air of another and more steadfast mental intercourse, but more and more certainly and ardently convinced the longer he breathes the sÉance atmosphere. No form of contagion is so insidious in its onset, so difficult to check in its advance, so certain to leave germs that may at any moment reveal their pernicious power, as a mental contagion—the contagion of fear, of panic, of fanaticism, of lawlessness, of superstition, of error. The story of the witchcraft persecutions, were there no similar records to deface the pages of history, would suffice as a standing illustration of the overwhelming power of psychic contagion. To illustrate with any completeness its importance in the production of deception or in the dissemination of error, would carry us beyond the proper limits of the present discussion. It enters at every stage of the process and in every type of illusion. Although it has least effect when deception is carried on by external arrangements, by skilful counterfeits of logical inferences, yet even then it enters into the distinction between a critical, skeptical, and irresponsive body of spectators, and one that is sympathetic, acquiescent, and cordial; it renders it easier to effect bold and striking impressions with a larger audience than with a smaller one; its power is greatest, however, where the subjective factor in deception is greatest, more particularly in such forms of deception as have been last described.

In brief, we must add to the many factors which contribute to deception the recognized lowering of critical ability, of the power of accurate observation, indeed of rationality, which merely being one of a crowd induces. The conjurer finds it easier to perform to large audiences because, among other reasons, it is easier to arouse their admiration and sympathy, easier to make them forget themselves and enter into the uncritical spirit of wonderland. It would seem that in some respects the critical tone of an assembly, like the strength of a chain, is that of its weakest member. "The mental quality of the individuals in a crowd," says M. Le Bon, "is without importance. From the moment that they are in the crowd the ignorant and the learned are equally incapable of observation."

VI

In this review of the types of deception I have made no mention of such devices as the gaining of one's confidence for selfish ends, preying upon ignorance or fear, acting the friend while at heart the enemy, planned connivance and skilful plotting, together with the whole outfit of insincerity, villainy, and crime. It is not that these are without interest or are unrelated to the several types of deception above considered, but that they are too complex and too heterogeneous to be capable of ready or rigid analysis. When deception becomes an art of life, consciously planned and craftily executed, there must be acting and subterfuge and evasion to maintain the appearance of sincerity. The psychology of the processes therein concerned is almost coincident with the range of social, intellectual, and emotional influences. Complex as these operations may be, they have, in common with the less intricate forms of deception, the attempt to parallel the conditions underlying the logical inferences which it is desired to induce. If we add this great class of deceptions to those already enumerated, we may perhaps realize how vast is its domain, and how long and sad must be the chapter that records the history of human error.

Ethics is so closely related to psychology—right knowing to right doing—that a brief hÆc fabula docet by way of summary may not be out of place. We find, first, a class of sense-deceptions which are due to the nature of our sense-endowment, and deceive only so long as their true character remains unknown. These are neither pernicious nor difficult to correct. Next comes a class of deceptions that deceive because we are ignorant of the possibilities of technical devices, such as those used in legerdemain, and pronounce upon the possibility or impossibility of a certain explanation in advance of complete knowledge. But still another class, and that the most dangerous and insidious, are the deceptions in which self-deception plays the leading rÔle. The only safeguard here is a preventive; the thorough infusion of sound habits of thought, a full recognition of the conditions under which the testimony of consciousness becomes dubious, an appreciation of the true value of objective scientific evidence, and an inoculation against the evils of contagion by an independent, unprejudiced, logical schooling. When once the evil spirit of self-deception, fed by the fire of contagion and emotional excitement, begins to spread, reason has little control. As Tyndall tells us, such "victims like to believe, and they do not like to be undeceived. Science is perfectly powerless in the presence of this frame of mind.... It [science] keeps down the weed of superstition, not by logic, but by slowly rendering the mental soil unfit for cultivation." With the spread of an education that fosters independence and self-reliance, with the growth of the capacity to profit by the experiences of others, with the recognition of the technical requisites that alone qualify one for a judgment in this or that field, with a knowledge of the possibilities of deception and of the psychological processes by which error is propagated, the soil upon which superstitions, psychic delusions, mental epidemics, or senseless fads are likely to flourish will gradually be rendered unfit.