Hans Driesch

German embryologist and professor of philosophy who was one of the last advocates of vitalism, the theory that life is directed by a vital principle and cannot be explained solely in terms of chemical and physical processes - a theory which he termed 'entelechy'. President of the Society for Psychical Research from 1926 to 1927.

Possibilities of Deception in Anticipatory Observation

 - Hans Driesch -

          THE PROBLEM of the precautions to be taken becomes of real scientific importance only when we come to consciously anticipatory observation, still leaving true experiment on one side for the time being. As opposed to 'anticipation' all spontaneous phenomena, apart from true telepathy, are provisional and of comparatively little importance from a strictly scientific point of view.

a. Physical Phenomena

We again begin with the physical phenomena, that is, we have to inquire how we can safeguard ourselves against conscious or unconscious fraud when we have progressed to the anticipatory observation of so-called telekineses, materialisations, apports, and hauntings, having obtained the impression after spontaneous observation that it would be worth while further to investigate the phenomena reported to us or possibly even experienced by us.

Unless definite haunted places are in question, the anticipatory observation will generally be carried out in so-called sittings (séances). Under these conditions the anticipatory observation is done by several sitters; this is a good thing, if only because it excludes purely subjective phenomena. There is no harm in the sitters submitting themselves at first to the requests of the mediums, who are usually of spiritualistic outlook and scientifically uneducated, to form a 'chain,' to sing, to play gramophones or similar instruments, to call on 'spirits,' and so on. Similarly, darkness may be allowed to begin with.

But it should be regarded as an imperative duty to free oneself as soon as possible from these conditions, or at any rate to try whether the phenomena will not 'come' without them.

The same is true of the sending out from the circle, at the command of the medium, of 'disturbing' persons.

It may very well be that the chain and the singing really help the phenomena, that certain sceptical or 'negative' persons really harm them, and that darkness or red light really is essential, as in photography. In view of our complete ignorance the contrary cannot be maintained with certainty a priori.

But these conditions are undoubtedly hindrances, and therefore the attempt gradually to do away with these restrictions is unquestionably advisable. If they could be abolished many types of precaution against fraud could be at once dispensed with.

I have already proposed elsewhere(1) that the attempt should be made to educate mediums by Coue's method of suggestion, that, either with or without hypnotisation, they should be repeatedly and convincingly 'suggested,' 'It will go all right in very strong red light (even in white light), without singing, without a chain,' and so on; this should be done twenty to thirty times and more. Success would justify the effort involved, even if only certain general obstacles to certitude were removed, without at once procuring complete certitude as to the reality of the phenomena.

(1) Journ. Amer. S.P.R. (1927), xxi. 66.

The replacement of darkness or weak light by good light is really of quite fundamental importance, and I am not afraid to say that I cannot admit as quite certain any paraphysical phenomenon that took place in darkness or even in a dull red light. Of course, this is not to say that all phenomena alleged to have taken place in good light are certain! For there are such people as conjurers and they are often very skilful! When I was travelling to China an Arab came on board at Port Said, who, without assistance and without preparation of the smoke-room, in which the performance took place, extracted living chickens, which afterwards ran about gaily, from the waistcoat pockets of the passengers. Nobody discovered how the trick was done, even though it was admittedly nothing but a trick!

We must turn now to a detailed consideration of the necessary precautions. A great difficulty here is the fact that both the medium and the sitters must a priori be regarded as 'suspect.'

Unfortunately amiable generalisations are worthless here. For man is a strange creature! Anybody who says, 'How could this person cheat? She is the daughter of a general, or of a professor; it would be insulting even to mention fraud,' forgets, in the first place, that conscious fraud is not necessarily in question, and, secondly, that even the daughter of a general or a professor can occasionally be a strange creature, perhaps possessed by an out of the way passion for self-expression, even if not merely by a taste for practical joking.

It is precisely an honest medium, as has already been said, who should look at this matter in a purely scientific way. He should not regard a reference to fraud as insulting, but rather as a consideration which is justified in view of the extraordinary character of the phenomena. And he should not forget that 'he' is not responsible for his subconsciousness. For who indeed knows his own subconscious? If we knew it directly and consciously it would no longer be subconscious; we can get to know it only empirically and indirectly, by means of its 'actions.' And empirical knowledge is always provisional and subject to correction; thus my subconsciousness may be quite different from the opinions I have concerning it to-day.

We now proceed to consider in turn the specific precautions that have to be taken against fraud of every kind in the field of the alleged paraphysical phenomena. Sometimes we shall have to consider the different types of phenomena separately; hauntings we leave altogether on one side for the time being.

A quite definitive decision in favour of genuineness will be much more difficult in every kind of alleged phenomenon, as has already been said, if complete darkness be present. This is true, at any rate, of the kind of sitting nowadays usual. I say expressly that this is true of the usual type of sitting. For I can imagine conditions in which a positive decision would be possible. If the medium's body has been strictly examined, if he then takes his seat under strict control, dressed in a one-piece garment without pockets, if the sitting takes place in a room in which the medium has never been or which was very thoroughly investigated before he came in, if the doors and windows of the room are locked and bolted from the inside, if I am alone in the room, apart perhaps from a few 'trustworthy' persons, all of them, however, similarly examined and dressed, then if something happens, a materialisation or an apport, I should decide for genuineness even if the sitting took place in complete darkness.

Such conditions of investigation have never yet been put into effect. The kind of control that has so far been practiced is this:

First, forming a 'chain,' that is, holding by all the sitters of each other's hands in the form of a chain. We said above that strictly speaking the chain is perhaps superfluous. Its advantage from the point of view of control is that no sitter has his hands free. This excludes fraudulent interference requiring the hands: for it would involve a conspiracy of two sitters to free each other's hands. Of course the hands must be held firmly and not merely be touched with the fingers. Otherwise it is possible in the dark to get one hand free by causing one's neighbours to touch different fingers of the same hand, thinking that they are touching the fingers of different hands. This is a trick that has often been practised.

Secondly, undressing the medium (not the sitters) before witnesses and dressing him in a kind of tights, as was done by Schrenck.

Thirdly, placing numerous needles with luminous heads on the medium's sleeves and trousers, and also on his boots. It may be noted here with special emphasis that the medium should never be allowed to wear shoes out of which he can easily take his feet; he should always wear laced or high boots which cannot be put on or taken off without using the hands. So far as I know this last condition has never been observed.

Fourthly, the holding of the medium's hands and feet by a reliable person.

Fifthly, the careful searching of the room, including the so-called 'cabinet,' if one is present, for wires, threads, or long thin rods (the reaching-rods of the English investigators).

Sixthly, in the case of telekineses, putting such a distance between the object it is hoped to have moved that it is out of reach of the medium and everybody else present.

In Schrenck's sittings these conditions were partly carried out, and the experiments conducted in his laboratory were certainly amongst the best in recent times. He made use, in addition, of the electrical method of control invented by Krall, which enabled any suspicious movement of the medium's arms and legs to be at once noted - if it worked properly.

The sitters, apart from the chain, were not controlled. They were 'trusted' - and I have no reason for saying that they were unjustly trusted, but of course that is only a conviction.

Price then applied this form of electrical control to all the sitters, with the exception admittedly, of the secretary, who, however, was also 'guarded' in later sittings. I do not know how reliably this extended electrical control operated.

Dull red light was the rule at the sittings both of Schrenck and of Price.

Something quite new in the way of control has recently been introduced by Osty in the French Institut Métapsychique, in sittings with Rudi Schneider(2). This is a somewhat complicated apparatus based on the use of an infra-red beam. It was demonstrated with this apparatus that a certain invisible and non-photographable 'substance,' capable nevertheless of influencing a beam of infra-red light, is exteriorised by the medium and produces telekineses under his unconscious mental control. Work on these lines, continued as carefully as it has been begun, will perhaps be able at last to produce a thoroughly convincing result.

(2) E. and M. Osty, "Les pouvoirs inconnus de l'esprit sur la matiere" (1932). A brief but very clear summary is that by Besterman, Proc. S.P.R. (1932), xl. 433ff.

Continuous efforts must in fact be made, with the help of physicists and technicians, to improve the methods of control. There can be no doubt that fully adequate methods of control can be attained, and only then will a decisive judgment be possible.

As has already been said, it would be particularly important if one could 'suggest' to mediums the ability to 'work' in good light. In such light, with the medium and all those present at two metres distance from the object to be moved, it being certain that no threads, rods or wires are present, a movement of the object would render a negative opinion quite impossible even without introducing complicated methods of control.

Of course good light by itself is not enough. Such light was present when I saw Mirabelli; but a careful search of the relevant rooms for threads and the like had not been made, and so the telekineses he produced were not acceptable as reliably genuine, though they remained in part very impressive.

In view of its very questionable nature I will say nothing of the 'direct voice.' What I saw of Valiantine in Berlin was a lamentable farce(3), and I am unable to form a personal opinion of the present position of the Margery mediumship. I made certain proposals for the improvement of the conditions in which this mediumship operated in 1926(4). Since then various improvements appear actually to have been made; but darkness still reigns.

(3) Bradley, who caught Valiantine fraudulently producing alleged finger-prints of deceased persons and who frankly published his discovery, at the same time continues to maintain the genuineness of this medium's 'direct voice,' on the ground of the alleged supernormal nature of the communications made by it. Now in Berlin the 'direct voice' was certainly also fraudulent; nobody who was present could doubt that, and the content of the voice was in the last degree feeble and meaningless. In order to enable Bradley to retain the supernormal nature of the content of the communications made by the 'direct voice,' it would be necessary to imagine some such circumstances as the following, though these would be applicable only to sittings other than those held in Berlin: the 'direct voice,' that is, the alleged direct vocal statements of a 'spirit' made without the intermediary of the medium's mouth, which is definitely fraudulent, would have to be regarded as unconsciously fraudulent; it would have to be supposed that it was the medium who spoke, but in trance and really acquiring knowledge supernormally. Then the mediumship would be of the Piper or Leonard type, but surrounded with an incidental and unconscious framework of fraud.

(4) "Zeitschrift fur Parapsychologie" (1927), P. 38.

The phenomenon of the so-called 'raps,' alleged to be the simplest paraphysical phenomenon, though actually, if it is genuine, an astoundingly strange one, usually occurs under conditions that exclude every sort of control against conscious or unconscious fraud.

Table-rapping in its physical aspect, that is, the raps as such, is in all probability a product of the subconsciousness of one of the sitters. The content of the rapped messages may nevertheless be supernormal, but would belong to the parapsychical phenomena.

Let us give a little further attention to 'apports,' that is, the sudden presence of objects in a specific place, under circumstances which make it impossible for these objects to have travelled there 'through free space' from their place of origin. These objects are often alleged to penetrate material bodies, walls for instance. If this most amazing of all amazing phenomena is genuine, it would be easier to admit certain other somewhat less amazing phenomena even if they occurred under conditions that were not fully satisfactory.

I have myself seen apports with two mediums. On one of these occasions the phenomena were decidedly impressive (a rain of violets in electric light); but there was no scientific control.

Unobjectionable conditions for the anticipatory observations of apports would be as follows:

All the sitters and the medium should be undressed under strict control and dressed in one-piece garments without pockets. The medium should sit on an isolated chair, near which there is no table. The room should be exhaustively examined. If under these conditions flowers or other objects suddenly lie on the floor, then apports exist. Needless to say, objects such as small stones, which the medium can hold in his mouth, would signify little.

It would be to some extent satisfactory even if, in good light, only the medium were dressed and seated in the manner described and if apports then occurred.

Here also it is not enough merely to have confidence, as for instance in the cases one still comes across where somebody describes how he searched the room, found it void of flowers, locked it, and left with the medium, finding flowers in the room on returning. There are such things as confederates and master keys.

In a richly endowed institute unobjectionable investigations of apports could easily be made. Mediums who claim to produce apports could be procured under a guarantee that they would not be prosecuted if they produced no phenomena.

The habit of bringing actions must in fact be discontinued by both sides, by sceptics and by believers. There must be no more actions either for fraud or for slander - at any rate in the field of purely scientific investigation. Matters are different in the case of stage performances and particularly those in which clairvoyance and prophecy are practiced for money, though to me tolerance appears the best course even here.

We must now speak separately of 'hauntings.' The study of these phenomena must begin with spontaneous observation and with the reports or rumours based on it. Then, if the matter is taken further at all, anticipatory observation begins, either of a specific person or of a specific place; for there are alleged to be phenomena of this type directly connected with places or with persons. Apparitions, in this context called ghosts, belong to the first type.

Only objective phenomena, such as the movements of objects, noises, even apparitions, should be described as phenomena of a genuinely haunting type. Subjective phenomena, such as the seeing of an apparition by a single person, should always be regarded as hallucinations, perhaps of telepathic origin. This is not to say that apparitions seen by several persons cannot also be hallucinations. This can be decided only by the photographic plate in the case of visual phenomena, or by a sound-recording apparatus in the case of auditory phenomena. So far as I know such an apparatus has never been employed. The use of it would considerably support, even though it would not definitively establish, the reality of the phenomena to which Mattiesen attaches such importance, those in which numerous persons, each in his appropriate perspective, are alleged to have seen an apparition.

The most general precautionary measures needed in regard to the alleged phenomena of haunting have already been discussed on p. 14, where spontaneous observation was in question. We saw that only after-control was then possible. If, however, a haunt is expected for any reason, then the necessary precautions, including fore-control, can be more strictly applied: thorough searching and sealing of the room, undressing and redressing of the medium in the case of mediumistic haunting, etc.

It is a fact, however strange it may seem, that the existing reports of hauntings yield an appreciable probability that these phenomena are genuine; nobody who really knows these reports can dismiss them out of hand. At any rate, hauntings have attained a much higher degree of probability than such phenomena as the direct voice, apports, etc., and it is certainly the duty of science to investigate them.

The best reports are those of Walter Prince(5), a very careful investigator, who is abused as a 'negativist' by some uncritical persons. But there are also reports, by Schrenck-Notzing for instance, which deserve careful consideration. The same is true of the communications made in a somewhat 'literary' form by F. von Gagern.

(5) References will be given later. Bozzano is one of our acutest theorisers, but unfortunately far too slipshod in accepting alleged facts.

We conclude this section with a few general observations. It has sometimes been suggested that we should be on our guard against mass-hallucinations in testing the reality of paraphysical phenomena; it has even been said that all positive or even sympathetic students are hypnotised.

We admit, as has already been said, that a single person can fall victim in such investigations to an autosuggestion leading to hallucinations, especially when an emotional element is present. But this possibility appears to me to be excluded in the case of observation by several persons, at least in the usual type of sittings.

In these the emotional element is lacking; indeed, such sittings are rather boring. And the objective fact, whether genuine or not, is simply there, as when a rod which before lay on the table now lies on the ground. Suggestion may occur in the case of materialisations, but it would have to be mass-suggestion. And mass-suggestion of non-hypnotised persons, however, if it occurs at all, is, in the first place, a very rare thing(6). In the second place, mass-suggestion appears to be excluded in this context because in such sittings as we are speaking of, irrespective of whether the phenomena are genuine or not, it is customary for all the observers together, and not successively, to exclaim, 'There it is,' or the like. In the third place, nobody knows what is going to happen. It would therefore have to be assumed that the medium, without speaking, communicates to all present an hallucination-provoking suggestion; but in that case the phenomenon would still be a supernormal one, though of a mental and not of a physical type. For we should then be confronted with telepathic mass-suggestion, which is a hitherto unknown phenomenon, though of course I do not question its possibility. There is, however, not the slightest evidence for it.

(6) So also Dessoir, "Vom Jenseits der Seele", p. 237. Mass-suggestions, if established at all, are certainly exceedingly rare, apart of course from the cases in which a doctor for curative purposes practices suggestion on Coue's lines on a group of patients simultaneously.

No decision is now possible as to the reports of such Indian phenomena as those of the mango trick, the mutilation and restoration of a human being, the rope-trick, the fire ordeal, etc. In these cases mass-suggestion may have been present - if they were not mere tricks; but if so it must again have been telepathic suggestion. At least, it must have been so when the fakir either did not talk at all or talked in a language not understood by the witnesses. For then nobody could have known what was going to happen at a given moment and yet all saw it a tempo.

So far as European investigations are concerned, at any rate, we can safely leave the hypothesis of suggestion on one side.

b. Mental Phenomena

We now come to the important section in which we have to inquire into the precautions necessary in the anticipatory observation of parapsychical phenomena. Here our results will be much more satisfactory in a positive sense than was the case in the physical phenomena which we have just discussed and in which the process of anticipatory observation was, in the strictest sense, limited to the act of 'awaiting.'

We are concerned here with thought-reading and with clairvoyance. For true telepathy is always either spontaneous or experimental, and to prophecy we are devoting a later section.

1. General

Anticipatory observation must be so arranged as to take into account the fact that in this field the investigator or investigators find themselves in the presence of a medium.

The medium is either lying or sitting in a so-called trance or is perhaps to all appearances not in trance. He then makes statements by speech or in writing about things which it is supposed could not be known to him normally. These things comprise, in the case of thought-reading, the mental content of another, and, in the case of clairvoyance, objective situations in the empirical world.

The supernormal element in these things is not the actual fact that the medium knows something about the mental content of another or about an objective situation. That which is supernormal is the manner of the acquisition of his knowledge. The percipient or medium, as we know, is, in the phenomena under discussion, in contrast to telepathy, the active participant; he 'wants,' even if only unconsciously, to acquire knowledge; in the case of thought-reading, he wants, as Lehmann once aptly put it, to 'tap' the knowledge of others. These others, that is, the agents, are as passive as are the percipients in true telepathy.

In the case of knowledge supernormally acquired by the medium from the mental content of another, that is, in thought-reading, the mental contents so acquired may be actual, momentarily conscious ones. There may also be contents that once were conscious but have now been forgotten; in that case the person from whom the knowledge originates, the agent, sometimes can and sometimes cannot remember the fact in question, even though investigation elsewhere shows it to be true. Further, the knowledge 'tapped' by the medium or percipient, may be or may have been in the possession of somebody present or absent.

We should thus have a mass of possible cases resulting from the combinations which follow:

  • The medium is or is not in trance.

  • The tapped knowledge was or was not actually present in the agent.

  • If not actually present it was or was not capable of being remembered.

  • The agent was present or absent.

The investigators have to take precautions against two groups of possible sources of error, those relating to the agent, that is, he who 'gives' out his knowledge (without knowing that he does so), and those relating to the percipient or medium, that is, he who supernormally acquires knowledge

2. Precautions in Regard to the Behavior of the Agent

Unconscious Indications

It is possible to give unconscious indications. But of course it is only necessary to guard oneself against this possibility when the agent and the percipient can see or hear each other. It will not always be possible to avoid this; but matters should at least be so arranged that the percipient cannot see the face of the agent. This precaution is naturally superfluous if the medium says things that the agent does not actually know; for his expression obviously can not give unconscious indications of things that he does not know.

Useful experiments in pseudo-thought-reading have been carried out in Kruger's Institute and by Marbe for the purpose of studying unconscious indications in cases of apparent telepathy and thought-reading. True unconscious whispering may be in question, but also mere movements of the mouth, nose and eyes. It is possible to acquire skill in observing such movements, and perhaps the medium has acquired such skill. So take care! It is best of all, as has already been said, entirely to exclude even the possibility of the perception by the medium of unconscious indications. In many of the experiments of Upton Sinclair(7) and of the English investigators this possibility was excluded, in the nature of things, by the great distance between the agent and the percipient; the same is true of many of Wasielewski's experiments, in which the agent was in Thuringen, the percipient at the Mittelmeer.

(7) Whose book "Mental Radio" (1930) was rightly described by McDougall as one of the best parapsychical books. It has been very thoroughly verified and endorsed by Walter Prince.

I merely mention the most commonplace methods of normal communication, such as the music-hall performances based on the so-called Cumberlandism or muscle-reading. Even in such performances there may be something supernormal; but their essential parts are quite certainly far from the region of the supernormal, that is, there is nothing at work but thought-transference by speech, writing, or feeling, except that the symbols employed are refined and uncommon.

Psychological Preferences

Marbe's investigations into psychological preferences present very valuable precautionary methods in certain cases, particularly those in which the investigations takes on a genuinely experimental character. If requested to think of a colour by far the larger number of people will think first of all of red and then of green. Among figures the 5 is preferred and among cards the ace(8).

(8) These preferences vary from country to country. Much work on them will be found in recent volumes of the Proceedings of the S.P.R. - Trans.

If the medium knows these facts thought-reading will be an easy matter for him and he will always obtain many 'hits.' And there exist many other similar preferences.

The best way to protect oneself against these sources of error is altogether to avoid those methods of investigation in which they arise. In inquiries which belong strictly to anticipatory observation and not to experiment, as in the researches with Mrs. Piper and Mrs. Leonard, preferences play no part. Nor do they in experiments with mediums of the type of Ossowiecki and many others.

Ambiguous Statements

It is more difficult, even in mere anticipatory observation, to guard against the vagueness and ambiguity of the statements made by mediums.

Hellwig has methodically carried out very important investigations in this field, investigations which retain their value even if it is granted to his critics that he has selected out of the mass of available cases only the 'bad' ones, passing over the 'good' examples. But the bad cases were there, and in regard to the question of acquiring certitude, a question the strict treatment of which should be valued by every serious psychical researcher, it is precisely these cases that are important, even if they are practically insignificant in relation to the mass of good material in certain long series of investigations. Many series, however, do not even contain any good material, so that Hellwig's observations in any case retain their importance.

Hellwig(9) asked a number of independent people what they would say if they were told that an object was in question which was described in these words: 'Longish, dark. One end pointed, but not altogether pointed. The dark end is flat.' This statement had actually been made by a thought-reader. Hellwig received two hundred different answers, only one person answering correctly ('key'). For there are obviously many objects to which this very vague description might to some extent apply.

(9) "Kosmos" (1930), No. 5.

Hellwig further showed a number of independent people a specimen of writing discussed in the case in which the alleged clairvoyante Frau Gunther-Geffers was prosecuted. He asked them what name was written down. Over twenty different answers were given, none of them correct. The name written down was alleged to have been meant for 'von Reibnitz'; one person read it as 'Dora Behrens'!

What exactly is the question at issue? The question is one we already raised in discussing spontaneous telepathy: that of coincidence between a fact and a statement concerning it. In other words, we are now concerned with coincidence specifically of content. For temporal coincidence, as in the telepathic communication of a death, does not arise here. The question asked is this: is the resemblance between a fact and the medium's statement concerning it a 'chance' resemblance or is chance excluded? In vague statements the possibility of a chance hit is very great, and consequently one cannot without investigation accept a hit as being necessarily a true one.

Nearly everything that I have experienced with German mediums belongs to this group of all too vague and consequently valueless statements. We saw above (p. 21) that vague statements about 'character' are of no value, and that statements about love, marriage, children, and the like, often have a probability of 1 in 2. Hence such statements also are without significance.

Rare, out of the way details must be given supernormally before the case, if all the other necessary conditions have been fulfilled, can be accepted as genuine.

The stricter psychical research is in this matter the greater weight will the genuine cases have even if the total number of cases is thereby reduced.

Naturally there always remains the possibility of a difference of opinion in estimating the value of the coincidence in any particular case, but in practice there are many cases that every student accepts - if he knows the literature well, which unfortunately is not always the case!

It may be added to Hellwig's critical remarks that in the case where the alleged supernormal statement 'longish, dark, etc.,' was made, there always remains the possibility that there was a genuinely supernormal 'perception' of a real objective key. All that can be said is that such a case is of no significance in itself. In apparently good cases of the supernormal acquisition of knowledge we often get what may be called schematic-intuitive statements, though of course more precise ones than in the case of the key. Mediums say that they 'saw' something which they did not at once 'understand' and which they consequently interpreted 'intellectually,' thus possibly introducing mistakes. Thus the intuitive schematic form of a statement cannot in itself be regarded as an adequate reason for doubting its genuineness. Here also care will have to be taken; we must naturally not forget that even a good supernormal schematic description will not always be capable of being recognised. For instance, during Wasielewski's investigations the medium once said that she saw him sitting in front of a box, with white and black lines running towards him. Another time she said that she saw him sitting high up, under him a light, on his right and left something like a wall. It turned out that on the first occasion he was actually sitting at a piano, and on the second occasion cycling through a thick wood. As these activities were not customary with the agent these cases must be regarded as good ones even though the percipient's statements were merely intuitively schematic. In Upton Sinclair's experiments the percipient's remarks go far beyond this, and similarly in the case of the mediums Piper, Leonard, Ossowiecki, etc. The Paris experiments in the 'reading' without contact of sealed letters by the medium Kahn are notable. These tests yielded nothing but hits, but they undoubtedly require to be independently repeated.

Errors of Memory

The agent has further to guard himself against mistakes in regard to his own memory, against what is technically called fausse reconnaissance, and against the deja vu. It happens only too often in daily life that in listening to a story we imagine that we already knew or learned or experienced it. It is further known that most people remember nothing of the experiences of their early childhood, but that they grasp with such strength what their relations and friends have told them, that they come to believe these experiences and to repeat them to others, perhaps with embroideries, as personal memories. It can similarly happen that in thought-reading the agent may imagine himself, quite wrongly, to have experienced the things the medium tells him. Verification is always necessary in such investigations.

A contrasting phenomenon is presented by the cases in which the medium tells the agent whose (in these cases latent) knowledge he taps something that the agent has completely forgotten and is unable notwithstanding all his efforts to recall, but which is discovered on verification actually to have been a bygone experience of his. In that case, if all the other conditions have been fulfilled, the phenomenon is a 'true' one.

3. Precautions in Relation to the Percipient

The precautions against deception so far mentioned are those to be observed by the agent, who has, as it were, to be on his guard against himself. The following precautions relate to the percipient or medium. This group of necessary precautions is even more important than the one we have just surveyed, because here conscious or unconscious fraud may be present, and not only error or carelessness, as in the case of the agent.

The first and most general precaution consists in preventing the possibility of the medium acquiring knowledge about the past lives of the persons with whom he may come into contact in the sittings.

The medium might learn something about dead people from gravestones in cemeteries, since most sitters are always glad to hear something about their dead friends. He could run through newspapers, and even letters, could question servants, and so on.

The English investigators protect themselves against these sources of error by introducing sitters under false names, and even, as in the cases of Mrs. Piper and Mrs. Leonard, by causing the mediums to be watched by detectives. Nothing suspicious was ever observed in the behaviour of these two mediums. Further, the servants in the house in which the sittings were to be held were previously changed.


Further precautions are necessary against so-called 'fishing' on the part of the medium.

Mediums often guess about and about, wait for affirmative or negative remarks by the sitter, and even look out, if the sitter is not forewarned (cp. P. 38), for unconscious indications, and then they make statements that seem hopeful, or 'fish' further.

The sitter should therefore be very cautious with affirmative and negative remarks and should exclude the possibility of giving unconscious indications. Such remarks as 'yes' or 'good' should only be made if details of quite overwhelming accuracy are given. Otherwise there is open a very prolific source of deception on the part of the medium. Great care should also be taken in putting questions to the medium. Questions can far too easily have the effect of leading questions and of 'suggesting' answers to the medium, in which case these answers lose all their evidential value.

Hyperesthesia of the Senses

It is conceivable that the medium, even if he cannot see the agent and even if he is in a different room, may possess so high a degree of auditory hyperesthesia that he involuntarily hears words whispered by the agent. It is known that such hyperesthesia exists in the hypnotic state, which after all is related to the so-called trance.

The sitter must protect himself against this source of error by testing the hypersensibility of the medium, unless the distance separating the medium from the agent is so great as to make such a precaution superfluous.

Obviously, if the medium taps knowledge not actually present in the agent this source of error does not arise.

Errors of Memory

Just as it was found necessary before to adopt a critical attitude towards one's own memory, so here we have to be careful in regard to the possibility of error in regard to the memory of the medium.

There obviously exists the phenomenon of forgetting, even of such complete forgetting as to make all recall impossible. But forgetting often, perhaps always, affects only consciousness, not the subconsciousness - and it is precisely the subconsciousness that is in all probability alone responsible for supernormal statements. We know already from the investigation of the hypnotic state, which in itself has nothing supernormal about it, how much can be forgotten by a subject's consciousness and yet be capable of being recalled in hypnosis.

Thus the medium may quite honestly say that he never knew this or that, and yet he may actually, perhaps in early childhood, have known the fact that is in question and that is now rising into consciousness.

This is particularly true of the languages, said never to have been learned, the emerging of which in parapsychical sittings so often astonishes people. For instance, a medium spoke Hindustani, which he had never learned - but it was found that he had been born in India and had had a Hindustani-speaking ayah.

With Mirabelli, who is said to speak a dozen languages which he never learned, I myself experienced only Italian and Esthonian, alleged to have been spoken through his mouth by spirits. But his parents are of Italian descent and he was accompanied by a young girl from Tallinn. Baueron the Aramaic of Theresa Neumann, of Konnersreuth, may be compared(10).

(10) Article in the "Munchener Neueste Nachrichten", 14 December, 1927.

The best established phenomenon of this kind appears to be the old-fashioned English of Patience Worth. Walter Prince(11) is a sufficiently careful investigator to have earned the attacks of the 'believers'; it appears to me that no loopholes are to be found in his critical precautions, and his conclusion is positive.

(11) "The Case of Patience Worth" (Boston 1927).


Others articles by Hans Driesch

The Possibility of Deception in Psychical Research

The Forms of Possible Deception in Psychical Research

Possibilities of Deception in Anticipatory Observation

Possibilities of Deception in Spontaneous Observation

Precautions in Experiment

Inadequate Precautions

Exaggerated Suspiciousness

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