569 B. Further experiments of the kind just described were carried out by Mrs. H. Sidgwick in 1890 and 1892 with the help of the same hypnotist, Mr. G. A. Smith, in the course of her experiments on thought-transference (see 573 A). I quote a few extracts from the account given (pp. 577-93) in the paper by Mrs. Sidgwick and Miss Alice Johnson on "Experiments in Thought-Transference" in Proceedings S.P.R., vol. viii. PP. 536-96, beginning with their summary of Gurney's theoretical discussion of his results.

Mr. Gurney discusses the possible explanation of his results in the... Proceedings S.P.R., vol. v. pp. 254-59. He assumes that the conditions adopted secure - as they are designed to secure - that no indications as to which finger is to be operated on should unintentionally reach the subject through the eye, or the ear, or by touch. There remain then three hypotheses: (a) that this knowledge may reach his brain by means of a delicate perception, conscious or unconscious, of temperature or air-currents, caused by the proximity of Mr. Smith's fingers; (6) that it may be conveyed from Mr. Smith's mind to that of the subject by thought-transference; and (c) that some direct physical influence in which the ordinary channels of sense are not concerned is exercised through Mr. Smith's hand on that of the subject1

Mr. Gurney considered that the ineffectiveness of Mr. Smith's hand unless his will was engaged at the same time seemed alone fatal to hypothesis (a), which was also rendered almost untenable by the difficulty of supposing that the delicate perception assumed could have been delicate enough to make it possible to distinguish Mr. Smith's hand from Mr. Gurney's held similarly over another finger at the same time. Hypothesis (b), Mr. Gurney says, "seems excluded by the fact that the physical proximity of Mr. Smith's hand (no less than his concentration of will on the desired result) proves to be a necessary condition," and he concludes that the balance of probability is greatly in favour of hypothesis (c) - a direct physical influence, exercised through Mr. Smith's hand, in which the ordinary channels of sense are not concerned.

This brief introduction seemed necessary in order to explain the state of the question and the bearing of our own experiments on it. These, as will be seen, still further confirm Mr. Gurney's view as to the untenableness of his hypothesis (a), because we have succeeded in obtaining the result with a thick sheet of glass between Mr. Smith's fingers and the subject's. They also exclude hypothesis (c) and remove Mr. Gurney's main objection to hypothesis (b) (thought-transference), because we have succeeded when Mr. Smith did not hold his hand over the subject's at all, but merely stood with folded arms looking at the finger to be affected. We therefore believe that the true explanation of the results is thought-transference or mental suggestion, received in some unconscious or "subliminal" manner by the subject's mind, and acting on his organism in the same way that an ordinary verbal suggestion may act. The process would thus be analogous to that supposed by Mr. Gurney to occur in hypnotisation at a distance.

1 Mr. Gurney explains this hypothesis at greater length on pp. 257-59, vol. v. He thinks that if this specific influence exists, as a property of living tissue, there can be no doubt that it depends on the brain of the operator; since his attention and will to produce the effect are indispensable, and the same proximity of his hand which produces the effect also removes it - the only change of condition being in his intention. It is clear, however, that the nervous condition of the operator is not simply reproduced in the subject - the hand operated on assuming quite a different condition from that of the hand that operates. Therefore, though finding its nearest analogue in induced electric currents, and though best, perhaps, described as nervous induction, [the influence] is essentially vital and sui generis".

Before proceeding to a detailed description of our own experiments, we may remark that even taking Mr. Gurney's alone, the balance of probability seems to us to be rather on the side of thought-transference than of a direct physical influence. His contrary opinion appears to us to rely too much on negative evidence, the force of which it is easy to over-estimate. In his unsuccessful experiments where willing without approaching the hand was used, the only observed difference in conditions was the intentional withholding of Mr. Smith's hand; but this difference may easily not have been the whole change actually produced in the conditions, and therefore may not have been the cause of the non-occurrence of the phenomena under observation. Our experiments show, in fact, that it was not the cause.

But we also think some of Mr. Gurney's positive results hard to interpret on any hypothesis of a physical influence acting immediately on the subject's nerves, and not through his brain by means of suggestion. We refer especially to the fact that occasionally the wrong finger was affected instead of, or as well as, the right one. For instance, in Mr. Gurney's experiments with little paper screens already mentioned, two fingers, the selected one and another, were protected by them, and in the first experiment both these fingers became stiff and insensitive. Now it is easy to see how this might happen if the result were due to "suggestion " - that is, to an impulse communicated to the percipient's brain which set the machinery to work to produce the nervous effect for the suggestion can easily be conceived to go wrong. If it was self-suggestion, due to the perception of the little screens through the senses, it might naturally affect both fingers alike; and if it was mental suggestion through the action of the operator's mind on that of the subject, it is easy to suppose that Mr. Smith's attention was equally directed to both the marked fingers, though his hand only pointed to one.

But it is hard to see how any specific influence from Mr. Smith's hand could affect the finger he was and the finger he was not pointing at, without affecting also the intervening ones.

Details of the Experiments.

For our own experiments we adopted the same arrangements as Mr. Gurney. The subject, who was always in a normal condition at the time of the experiments, sat with his hands passed through holes in a screen which extended sufficiently above and on each side of him to prevent his seeing the operator or his own hands. The hands were spread out on a table, and the finger to be operated on was silently indicated to Mr. Smith behind the screen by one of ourselves either by signs or in writing. Mr. Smith generally said nothing while an experiment was going on, and he remained behind the screen until the testing was finished. The subject was frequently engaged by one of us in conversation on topics outside the matter in hand during the process of making the finger insensitive, but sometimes we encouraged him to attend to his own sensations, with results which will be described below. When we believed the in-sensitiveness to have been produced, we ascertained, without moving the screen, which finger it was in by touching the fingers with the point of a pencil or some other convenient instrument, taking care to attack them in varying orders, sometimes beginning with the selected finger and sometimes taking it later in the series, so that no indication as to which finger we expected to find affected might be given by the order of testing.

Occasionally the testing was done by one of us who was ignorant of which finger had been selected. Rigidity was ascertained by telling the subject to close his hands, when the affected finger remained extended. We often tried this before testing for insensitive-ness, because it was free from the objection that in testing we might possibly ourselves indicate the finger. In some experiments we attempted to ascertain roughly the degree of insensitiveness by means of a small induction coil. To this we shall recur later when we discuss the nature of the effect produced.

Our experiments may be divided into six heads, according to the position and procedure of Mr. Smith.

[I omit the details, and give only the summary of the experiments made with the subject P. as follows: - ]

[The writers describe fully the means they used to test the anaesthesia, the degree of anaesthesia attained, and the means used for restoring sensibility. The next point described is one which, as they say, affords further strong evidence of the genuineness of the experiments, since the subjects were quite unaware that the observations were being made, "such points never being discussed in their presence, even when they were hypnotised."]

1 The writers explain this expression to mean that Mr. Smith's hand was held above the selected finger, his fingers pointing downwards towards it, at a distance varying up to about four inches from it.

Sequence of Effects.

An interesting point observed was that the loss of sensibility seemed to spread from the lower part of the finger upwards, and when the effect was slight the tip of the finger only was affected. We have recorded fourteen cases in which either the lower part only - or the lower part first - became insensitive, or more insensitive than the upper. The only case observed in which this rule did not appear to hold good was one (No. 55) in which - after an attempt longer than usual, viz., from five to ten minutes - the only part of the selected finger (the right thumb) that became insensitive was the inner side of the proximal joint. Another possible exception to the rule was an experiment with Miss B., in which the part selected to be made anaesthetic was a spot in the middle of the back of the left hand. Here the anaesthesia extended both above and below the spot, over the metacarpal and proximal joints of the middle finger.

Recovery seemed to proceed in the opposite direction, the sensibility spreading downwards towards the tip of the finger. It was only possible to observe this in a few cases, as recovery of the whole finger, when upward passes were used for the purpose, was generally very rapid. One case is recorded when the sensibility was completely restored by two such passes. In seven cases, however, we detected the gradual recovery referred to, which always followed the rule given.

The recovery of motor power and of sensibility was not always simultaneous. We have noted five cases in which the sensibility was recovered first and none in which the motor power first reappeared. Also, in making the experiments, the motor power was sometimes lost while the sensibility was wholly or partially retained (this was noted in five cases); but we never detected any case in which the loss of sensibility extended further than the loss of the motor power. In other words, it seemed that the motor effect could be produced both more easily and more completely than the sensory.

These latter observations, though only made casually in the course of our experiments, are in accordance with the general experience of other investigators. In the paper already referred to [518 D] on the influence of self-suggestion, it is said that " muscular rigidity [was the] most general form of phenomenon produced by self-suggestion," whereas local anaesthesia appeared more rarely. It is well known also that muscular rigidity is one of the easiest effects to produce by verbal suggestion.

Sensations Described by the Subjects in the Course of the Experiments.

When their attention was directed to their hands, the subjects were sometimes aware of peculiar sensations in one or more of their fingers during the operation. Mr. Gurney found this with two of his subjects, after he had experimented with them for some time and got them to attend to their sensations during the process, and the finger in which they occurred was nearly always the one under experiment. The prevailing sensation was cold, sometimes also "pins and needles," "numbness," and the like {Proceedings, vol. v. p. 15).

Both P. and Miss B., when asked to attend to their hands, often mentioned a sensation of cold in the selected finger, and if we tested at once we generally found its sensibility reduced below the normal. The difference of temperature, if it existed at all, was not such as to be perceptible to ordinary touch. The sensation of cold soon went off, and the finger then became completely anæsthetic. It would, of course, be very easy - especially under the circumstances of the experiments - to imagine such a feeling as this, but its association with the right finger was certainly significant. The sensation, however, sometimes occurred in the wrong finger, but then anaesthesia never followed with P., though it occasionally did so with Miss B....

Care was, of course, always taken, when the subject first spoke of the sensation, to avoid giving him hints as to whether the finger he mentioned was the one we had selected for experiment. After a time we left off encouraging him to pay attention to his sensations, for fear of rendering the fingers too susceptible to any chance suggestions. [Some experiments illustrating this are next described].