The evidence reported for Extra-Sensory Perception is very varied in character, especially if we include the less experimental and more complex types of phenomena. First of all in importance is the division of this evidence into perception of mental conditions (telepathy) and of physical objects (clairvoyance). And, secondly, these may vary as to the spatial conditions concerned; i.e., the images or objects may be distant or nearby. Third, there may be a time variable as well, along with either condition mentionedthe image or objective event may be a past, present or future one. Fourth might be mentioned the wide range of experience or objective facts that seems to be perceivable extra-sensorially; feelings and emotions; various cognitive experiences, of perceptual or imaginal origin; complex purposes and attitudes or sentiments, and objective facts of almost any conceivable type. And so on; the limits of evidential variety are not known because the principles are not known and recognizable.
There is also a large group of phenomena of parapsychic nature that are not easily determined to be due to simple E.S.P. They constitute most of the naturally or spontaneously occurring parapsychic phenomena, such as veridical dreams and waking hallucinations. For one thing, they not infrequently carry the suggestion of agency of an incorporeal personalityas in apparitional monitions, for instance. And, again, there is often possible question as to whether the senses may not really be involved and the event be indeed a parapsycho-physical one, as, for example, in collective and simultaneous hallucinations of a veridical nature. For these and other reasons, these uncontrolled parapsychical occurrences are not ideal material for a study into the questions we have undertaken here to investigate, although they are often most impressive and interesting. They have served, however, to awaken attention to the problems and, indeed, to direct interest considerably beyond our present questions to the other divisions of the parapsychological field.
In the early years of the Society for Psychical Research in England there were extensive collections made of reports of spontaneous parapsychic
Between these spontaneous parapsychic phenomena and the results of more definitely experimental investigation of the subject, there is an
There have been some apparently very carefully conducted studies reported on parapsychic sensitives of the type called "psychometric mediums", who appear to be able to give knowledge, parapsychically obtained, concerning absent and unknown persons (who may be living or not) when a token or "object of contact" belonging to the person concerned is placed in their hands: Dr. Pagenstecher's report 2 of the work of Senora de Z., Prof. Oskar Fischer's study of Raphael Schermann 3, Tischner's cases in "Telepathy and Clairvoyance" 4 under the heading of (his suggested improvement of the name) "psychoscopy", and Dr. W. F. Prince's study of Mrs. King. 5 In the last named of these studies the calculation of the probability on the chance hypothesis of obtaining the results actually given yields a very impressive figure. And while I am here classifying this work among the observational, rather than among the more clearly experimental investigation, I wish to make clear at once that this is not to belittle it; for, with the sensitive concerned, it probably was the best
The early experiments, then, dealt with undifferentiated E.S.P.; either telepathy or clairvoyance, or both. The fact that they were called experiments in "thought-transference" or a little later in "telepathy" merely shows the pre-experimental belief of the investigators. But, in view of the fact that the foremost need at that stage was to discriminate rather between E.S.P. in general, on the one hand, and the sensory and chance hypotheses on the other, the work was of great value. The experimental design consisted first in the choice of material rendering computation of chance expectation easy and of making possible an estimation of the anti-chance value of the deviation from chance; thus, playing cards, lotto blocks, numerals of a chosen range and the like, were used, all with known probability in guessing. Second, various conditions were obtained In all this work the results were sufficiently striking to leave no doubt as to the exclusion of the hypothesis of chance. Even when the nature of the material was not such as to permit calculation of mathematical odds against the chance theory, the percentage of successes was impressive enough to discourage doubt. The explanation then was either one of E.S.P. or of some normal mode of perception, involving conscious or unconscious evasion of the conditions intended to eliminate the senses. The only seriously proposed alternate hypothesis was that of "involuntary whispering" suggested by Hansen 2 and Lehmann, psychologists, of Denmark. In 1895 they offered this explanation of the results published in the Proceedings of the S.P.R., claiming to have demonstrated in the laboratory the adequacy of their view. But after Professors Henry
Not all attempts made by investigators to demonstrate " telepathy" in this early period, the 80's and 90's, however, were so strikingly successful. Prof. Charles Richet 5 of Paris in 1884 made 2,927 tests on ordinary individuals guessing card suits, and got very low results, still, however, above chance by a margin of 57. This is between 3 and 4 times the probable error, and slightly under the minimum commonly taken as a significant result. He made, however, an interesting observationthat those who were worked for long series of over 100 did not do so well. And if the shorter series (those of under 100) are taken alone, 1,833 trials give 510 successes, which is 52 above chance or over 4 times the probable error. Max Dessoir's experiments 6 with drawings for material are not nearly so striking as those of the Smith or the Guthrie series; in fact, to the ordinary judge, they seem very poor. Yet, when an adequate method of evaluation was developed by Dr. W. F. Prince (B.S.P.R. Bulletin XVI, pp. 104-114) the drawings become clearly significant. Large numbers of tests were made on ordinary citizens both in England and America with a view to getting at the commonness of the " telepathic" ability. 12,130 trials were made in America, directed by Professors J. M. Peirce and E. C. Pickering, with results only slightly over chance expectation. 17,653 were made in England and reported by Gurney; these gave 347 above chance. This is at a low rate of scoring, comparatively; but, due to the large number of trials, it is significant, with odds against the chance explanation of 20 millions to one. Yet impressive as are such figures, they are small in comparison to the odds against chance attained in only 497 of the tests made with the Creery sisters and limited to the condition that none but the investigators knew the object selected. These 497 trials give odds of septillions to one against the chance theory. 7
In France the Schmoll and Mabire series, 3 in Germany Schrenck-Notzing's, 4 in America the Rawson 5 experiments, and in England the Wingfield series 6 of 3,024 trials on number-guessing (with successes 10 times the chance expectation) and about half a dozen others of less importance went on to strengthen the argument for a function beyond chance, fraud and mal-observationfor a parapsychical mode of perception. As to what it was, what its relations might be to physics, to biology, to the rest of mental life, there was very little discovered. But the fact itself was amply proved over and over. (For a better and fuller review of the experimental work thus far mentioned see B.S.P.R. Bulletin XVI, by Dr. Prince.) Curiously enough, however, the fact seems to require proof over and overmany, many times. For we find in the 20th century that Bruck, 7 a physician in Germany, Warcollier 8 in France, Coover, 9 and Estabrooks, 10 psychologists, and the famous novelist, Upton Sinclair, 11 in America (to mention only a few), have all produced fresh series of experiments primarily to answer the first questionDoes it occur?as if it were still an unsettled question. This will, I predict, be one of the more amazing facts for the future historian of science. And after reading Bruck and Warcollier and
The Sinclair book, "Mental Radio", does the great service, first, of reaching a wider public with very good and seemingly reliable results. It is rather of the systematic observational type than the more purely experimental. But there are some good distance experiments and an interesting introspective report by the percipient, who is Mrs. Sinclair herself. The exhaustive analysis of the original materials by Dr. Prince in B.S.P.R. Bulletin XVI adds a great deal to its value, and includes the independent and confirmatory tests on Mrs. Sinclair made by Professor William McDougall. Prof. Coover seems to have regarded his own work as negative and in many respects it was. But it seems pretty clear that he might have obtained more positive results and perhaps made considerable contribution by the very simple device of repeating the tests with those who succeeded best the first time. Even as it was, his 10,000 tests on "telepathy" (undifferentiated E.S.P.) and clairvoyance, yielded 294 successes as against chance expectation of 250 (p. equals 1/40). This deviation of 44 is over 4 times the probable error and would be generally regarded as statistically significant. Prof. Coover does not appear to have discovered this contribution which he made to the subject. But, what is much more important, the bulk of this positive deviation was contributed by a few of his 100 subjectseight in numberwho were among the highest in both
Dr. Estabrooks took the same type of subject, the average college student, and, using playing-cards also, found some evidence of "telepathic" ability in them. His conditions were excellent for excluding sense perception. The best points of his work were (1) some evidence of a lowering of the scoring-rate with progress through a run of 20 trials, the last 10 yielding less than the first ten. And (2) the fact that one group ran considerably below chance expectation when asked to run a second series, at a longer distance than the first. These, too, are interesting leads had the investigator been able to follow them up. He explained the decline in the run as due to "fatigue" (presumably of the "telepathic" function) and the drop below chance in the special instance as perhaps due to space limitations. Another variation of E.S.P. research is represented in the inclusion of other species in the range of "subject material". The more experimental of the animal parapsychic studies are those by the late Prof.
These animal cases have an especial interest for two reasons. One is the fact that in them the conditions often approximated pure telepathy as distinguished from the telepathy-with-clairvoyance-just-as-possible type of experiment which we have been reviewing thus far. Prof. Bechterew merely thought of the object in the room or in the adjoining room with which he wanted the dog to performi.e., he did not otherwise single it out. Supposedly it had no other isolation than the mental choice he exercised. There was thus an inadequate basis for clairvoyance, it would appear. In the Lady experiments I looked at the blocks, with eyes screened. This is not so free from objective selection, then, as is the other case. The second point of interest is the fact that Lady, the filly, lost her ability to perceive or to be controlled extra-sensorially (at least, as far as our tests could determine) after about a year of demonstration, and came to depend upon the rather obvious movements of the trainer for guidance, movements which, of course, we had had to eliminate during the earlier production period. This loss of ability in an E.S.P. subject has had other examples, notably the several Creery sisters, and Prof. Brugmann's subject, Van Dam, and perhaps others. It will be of especial interest in connection with this report. Another diversion in type of experiment, while we are still dealing with undifferentiated E.S.P. conditions (though they are still commonly called "telepathic"), is the condition of distance between agent and percipient. There was failure under this condition in the Smith series (except for very short distance) and success in the Sinclair tests. We have yet to review the Usher and Burt 4 tests made at a distance of from 120 to 960 miles, yielding in 60 trials with playing cards 4 successes complete and 14 right in value. This is at a very good rate of scoring but the number of trials is small for a conclusion. They did much better in the same room, getting 9 hits in 36 trials. The Miles and Ramsden 5 long-distance tests were made by having the percipient, Miss Ramsden, record daily
certain hour (7 P.M.). Miss Miles then got objective records, pictures, etc., for all of her setting that she could. Out of 30 trials, 13 were regarded as successful, barring what would conceivably be accidental. This series was not very experimental, it is obvious, but most critics have been impressed by it, in spite of its difficulty of mathematical evaluation. Another similar series is reported by Mr. Wales and Miss Samuels, 1 and is likewise difficult to judge, although impressive in its totality. The trans-Atlantic series conducted by a Paris group directed by M. Warcollier and a New York group under Prof. Gardner Murphy of Columbia I have not been able to find in print, but critics who have seen the results seem to regard it as difficult to evaluate and inconclusive, 2 as are likewise regarded the results of the two radio-broadcast experiments in "telepathy", the first conducted by Dr. Murphy, broadcasting from Chicago, and the second by Dr. Woolley, 3 from London. The sequel-series of experiments following the Woolley-broadcast that was carried out by Mr. S. G. Soal 4 was negative. So we may say, it appears, that of the reported experiments in "telepathy" with distance, the short Sinclair-Irwin series of seven drawings made at 30 miles from the agent, is perhaps the best. (See. B.S.P.R. Bulletin XVI, pp. 9-15.) This brief sketch is far from complete, even in the mere mention of titles, so extensive has the literature become. Especially in reference to continental European work is it incomplete. The work of the Russians, Dr. Kotik 5 and Dr. Chowrin, 6 that of the French Dr. Geley on Ossowiecki, of the German, Dr. von Wasielewski 7 on Miss von B. (with whom Dr. Tischner also worked) are examples of omissions. But there is great similarity in all this work, and we have given, I think, a fair notion of the field and its advanceor lack of it. Similarity of work in this field does not mean any extensive following of the work of others, but rather an ignoring of its conclusions and a starting all over again "to establish the fact" first of all (a phrase that is repeated so often that it becomes commonplace after 50 years of research and almost as many researches; and the same ground is covered, with many of the same difficulties that others have had and with the same general degree of success, very often). In 1932, fifty years after the Creery sisters investigation by the S.P.R., it publishes Mr. Soal's long research
The following general points seem to stand out as worth noting in the past contributions from these "telepathy" experiments: first, the evidence is (to one who labors through it all) overwhelmingly convincing of some extra-sensory mode of perception. That this includes the perception of mental states of a wide range of variety is also clear. That the hypnotic trance is not necessary, but is a possible "telepathic" working condition, seems also proved. Several interesting cases of loss of ability with lapse of time are recorded. Some decline of rate of success with length of the run is suggested by Richet and Estabrooks. Suggestion is made that certain drugs may help, but the only evidence is that of Brugmanns, who found improvement with alcohol (30 gms.), but only 29 trials are reported. The agent's greater tendency to fatigue and headache is referred to by several (Lodge, Guthrie, Sinclair), and the general need for passivity and serenity on the part of the percipient. Most of these points are fairly clearly indicated, if not established. Strangely enough there has been comparatively little experimental work on the seemingly simpler phenomenon of clairvoyance. This is, perhaps, an effect of the large influence that spontaneous occurrences have had upon the course of parapsychological thinking. These more often seemed telepathic rather than clairvoyant in nature. Still it is a remarkable fact that clairvoyance has been so neglected that it has never been thought necessary to eliminate it by condition from telepathy experiments. Consequently all the phenomena of these have been possibly also clairvoyant in nature. Prof. Coover even used card-guessing in the presence of the card as a control on the telepathic seriesthus allowing clairvoyance to operate but being so sure it did not function that the results were taken as chance products. (They were, however, above, by about twice the p.e.) The same loose condition has existed in all the telepathy experiments I am acquainted with; but, of course, with no danger to conclusions so far as concerns the demonstration of extra-sensory perception. While we have had this undifferentiated E.S.P. as regularly possible in the so-called "telepathic" tests, there were some where it seems unlikely that clairvoyance played much part. In Prof. Brugmann's experiment with Van Dam, he looked down through a glass-covered hole in the ceiling at Of pure clairvoyance we have had a few series of tests, rather similar to the "telepathy" data in quality and in range. Prof. Richet deserves credit for the first systematic experimentation in clairvoyance. 1 His tests made in Paris in 1888 with Leonie B. in hypnotic trance, using playing-cards sealed in opaque envelopes, were very successful. Leonie got 12 cards correct (probability of 1/52) in 15 trials and in a later series 5 in 25 (after having been transported to England and back, where a negative series was carried out). The odds against getting 12 hits in 15 trials on playing cards on chance alone is given by Richet as 1 quintillion to 1. There were also the experiments of Dr. Backman 2 of Sweden in the 90's, in which he put his subjects into hypnotic trance and commanded them to "visit" specified points at some distance and report what they "saw". They were able to perceive parapsychically to a degree that, if the report is acceptable, leaves little doubt of the fact of E.S.P. The exclusion of telepathy is not as clear-cut as is desirable and his results are, unfortunately, not capable of definite evaluation. There is not sufficient experimental character to such observations to enable definite conclusions to be drawn regarding the successful exclusion of such factors as infer-ability, guidance by unconsciously given indications, laxity in observation and coincidence. One does not see in the text, however, any ground for these alternative explanations. In 1895 Mrs. Verrall 3 tested pure clairvoyance on playing-cards, in conjunction with tests of hyperaesthesia and its possible functioning in parapsychic tests. She found that, under her conditions (which deliberately permitted it), hyperaesthesia of sight and touch could function to a degree, but that there was something more, presumably clairvoyance. Tischner reviews Kotik's work on the clairvoyance of his subject Lydia, carried out in Russia in 1908: Tischner's review is inadequate for a judgment of the original work; but he states his conviction that some of
Miss Jephson published in 1928, the results of 6,000 tests for clairvoyant perception of suits of playing-cards, made on 240 people, yielding results that average somewhat above mean chance expectation and, with the number of trials given, pass well beyond the minimum for significance. She obtained 1832 hits on suits or 332 above chance expectation, which would be approximately 14 times the probable error. Her results in pure clairvoyance compare roughly with those of Estabrooks on "telepathy"i.e., with both telepathy and clairvoyance possible. I quote the following figures of comparison from Miss Jephson's article: Dr. Estabrooks Miss Jephson Chance Total color right 56.5 55.1 50 Total suit right 28.5 30.5 25 Early guesses, color right 55.7 57.9 50 Early guesses, suit right 30.6 30.9 25 If the more experimental studies of clairvoyance were regarded as the only "pure clairvoyance" material, the evidence would not be at all overwhelming. I think it would be good but in need of much repetition. Even so, it is far ahead of the definitely experimental evidence for "pure telepathy", for of such there is nothing on record, to my knowledge. And, if we accept provisionally the evidence from the "telepathy" tests in which clairvoyance was not excluded, we may as well accept the evidence for
With practically no pure telepathy experiments and few pure clairvoyance tests, we have little or no basis of evidence for a study of relations between these two phenomena. Kotik's Lydia did both clairvoyance and telepathy (without excluding clairvoyance, so far as Tischner's review shows), and Wasielewski and Tischner's Miss Von B. did likewise. Coover's subjects did card-guessing in their barely significant way, under the same two conditions, pure clairvoyance and telepathy-plus-clairvoyance. But we cannot draw any conclusions about results from such conditions. The need for an experimental separation of the two is strikingly clear, all the more so since most students of the subject have had hypothetical views of some kind as to the relationship. In a very general way the Frenchmen, Richet, Osty and Geley, have preferred to think telepathy a special case of a general clairvoyance ("cryptesthesia", Richet's term, "metagnomy" Boirac's term). The English and American students have been slow to recognize clairvoyance, as is shown by the lack of any definite test of it in those countries until Miss Jephson's in 1928 and by their long ignoring the need for excluding it from telepathic experiments. There has been some bias against clairvoyance in Germany too, as is illustrated by Prof. Oesterreich's attempt to explain clairvoyant phenomena by telepathytelepathy expanded to unlimited dimensions. Barrett and Myers have theories for telepathy, but not for clairvoyance. Both Myers and Mrs. Sidgwick have suggested that there are probably connections between the two. 1 Tischner and Wasielewski are of the same mind. 2 A final phase of this review concerns the various hypotheses proposed to explain E.S.P. These fall into two groups in generalphysical hypotheses and non-physical. The physical hypotheses are the more numerous and popular, as well as the more elaborated. But in a general way they are all radiant or wave hypotheses, since this is the only physical principle available as yet for such theorizing. Even Ford's electron theory becomes as good a wave theory as any, since electrons are discovered to conduct themselves in the undulatory way.
The physicist, Sir William Crookes, perhaps the first general theorist of the field, proposed in 1897 1 the theory that telepathy might be due to high frequency vibrations of the ether generated by molecular action of the brain of the agent and received by the percipient's. He was conscious of the difficulty his theory encountered in the inverse-square law of decline of intensity with distance, but felt that our ignorance might be cloaking some principle which covers this point of difficulty. Another eminent physicist, Professor Ostwald, 2 has proposed a physical theory for telepathy, offering an energetic theory which assumes the transformation of known physiological energies into unknown forms that can be projected through time and space, received by the percipient and reconverted to known forms. But the great physicist of "energetics" had no evidence from his science to show that energies can be projected toward a goal, unless through a material channel. The energies radiate on a spherical front, so far as we know them. Sir William Barrett, another physicist, in argument against a physical theory of telepathy, 3 reminds us that the radiation theories would require, to reach 1000 feet, 1 million times the intensity of the transmitted telepathic stimulus that is required for one foot, and concludes that "it is highly improbable that telepathy is transmitted by waves radiating in every direction, like light from a candle." He quotes Myers, Mrs. Sidgwick and other eminent students as of like opinion concerning telepathythat it is a psychical, rather than a physical, phenomenon. Myers was especially opposed to a physical, and insistent upon a psychical, theory. But of what sort of a theory a psychical one is we have very little understanding, other than the fact that it is not physical (i.e., mechanical). Turning to the more comprehensive theories that embrace both clairvoyance and telepathy, we find three which are very wide apart in viewpoint and which will serve here to represent widely different possible
Tischner 2 invokes a theory of super-individual or collective mind, which serves as a common reservoir. He quotes E. von Hartmann as explaining telepathy through "telephonic connection with the Absolute" and aligns himself with this view. The connection is, he believes, through the "subconscious mind". This hypothesis is less definite and, perhaps, less extravagant, as some would regard it. But, in essence, it leaves us no more advanced toward explanation than Prof. Hyslop's suggested hypothesis. For we have to explain the business of "fishing" in the "reservoir" of the absolute or the collective mind quite as inevitably as if we just omitted all that, and assumed a direct contact between agent and percipient or object and clairvoyant. If we should need to bring in these other complications, "spirits", "reservoirs", etc., as inferred accessory factors in telepathy and clairvoyance, it would be fully acceptable to do so; but let us not obscure the fact that they do not explain telepathy and clairvoyance at all. They only complicate it. For all "absolutes" and "spirits" would have to perceive extra-sensorially themselves. These two theories, then, leave us as we were. Ford's theory 3 is a hard-boiled physical one, an electron-theory. The electrons come either from the brain of the agent or from the object, and when they come off in certain complexes they convey to the brain of the percipient the stimulation which leads to perception. A given "electron-complex" can stimulate a corresponding "engram-complex" in the percipient's brain, provided the percipient has previously established such an engram-complex through experience of the perception in question. This previous set-up is essential, because there is required the existing engram-complex in the percipient's brain which through "homophonous and synchronous" vibration may be aroused by an appropriate electron-complex, and perception effected. Thus the thought of a card-figure would give off from the agent's brain the same electron-complex as would the card-figure itself, both exciting the same engram-complex.
For a summary of the chapter, one may say that the evidence for general E.S.P. is good but the theories are bad; and our knowledge of the phenomena needs refinement through variation and improvement of conditions. We need tests for pure telepathy and more of them for pure clairvoyance, made under conditions that enable easy evaluation of significance, provide safe exclusion of other modes of cognition, and introduce variation enough to suggest the relation of E.S.P. to other processes and lead to its natural explanation.
15:1 By Gurney, Myers, and Podmore; Soc. Psy. Res. (London), 1886. 15:2 Longmans and Co., London, 1903. 15:3 Trans. by Stanley DeBrath; E. P. Dutton, New York, 1923. 15:4 See Human Experiences, B.S.P.R. Bulletin XIV. 16:1 See the interesting contribution in The Divining-Rod, Barrett and Besterman, London. Also Chap. IV, Richet's Thirty Years of Psychical Research, Macmillan, 1923. (Trans. by Stanley DeBrath.) 16:2 A.S.P.R. Proc. Vol. XVI, New York. 16:3 Experimente mit Rafael Schermann, Urban, Berlin, 1924. 16:4 Harcourt, Brace and Co., New York, 1925. 16:5 A.S.P.R. Proc. Vol. XVIII, New York, 1924, pp. 178-244. Another great case that belongs perhaps half-way in this department of the subject but is somewhat more experimental than these is that of Prof. Gilbert Murray, as reported by Mrs. Verrall, Proc. S.P.R. 29: pp. 64-110 and by Mrs. Sidgwick, 34: pp. 212-274. Prof. Murray usually requires a "point of contact" (a hand-clasp), but not one connected with the situation in question, and his work seems to be more telepathic than clairvoyant also, though the writing and speaking by the agents are required, and we cannot, therefore, be sure of telepathy. 18:1 Proc. S.P.R. Vol. II, pp. 189-200, 1884. 18:2 Hansen, F.C.C. and Lehmann, A., Uber Unwillkürliches Flüstern, Phil. stud. 17: pp. 471-530, 1895. 19:1 Proc. S.P.R. 12: pp. 298-315, 1896-1897. 19:2 Psych. Rev. 3, pp. 198-200, 1896; 4: pp. 654-655, 1897; Science, 8: p. 956, 1898. 19:3 James: Messrs. Lehmann and Hansen on Telepathy, Science, 9: pp. 654-655, 1899. Prof. Lehmann's words are: "not yet established (bewiesen)". 19:4 Lehmann, A., Aberglaube und Zauberei, 2d Ed., Stuttgart, Enke, 1908. This statement is based on Prof. Coover's Abstract, Experiments in P.R., Stanford, 1917, pp. 33-35. 19:5 See Abstract, Gurney. E., Proc. S.P.R., 2: pp. 239-64, 1884. 19:6 Phantasms of the Living, Vol. II, pp. 642-53, 1885. 19:7 Phantasms of the Living, Vol. I, p. 25. 20:1 For a review of this work consult Myers, Human Personality, 2 vols., Vol. 1: p. 568 20:2 P. 125, Vol. 1, A History of Psychology as Autobiography, Ed. by Murchison, 1930, Clark University Press. 20:3 Proc. S.P.R. 4: pp. 324-337; 5: pp. 169-215. 20:4 Proc. S.P.R., 7: pp. 3-22. See also Dr. W. F. Prince's review and criticism, B.S.P.R., Bulletin XVI, pp. 126-128. 20:5 Proc. S.P.R., XI: pp. 2-17. 20:6 Phantasms of the Living, I, p. 34, and II, p. 653. 20:7 Scientific American, May, 1924. 20:8 La Télépathie, Paris, 1921. 20:9 Experiments in P.R., Stanford, 1917, p. 640. 20:10 B.S.P.R., Bulletin V, p. 28. 20:11 Mental Radio (Sinclair), Los Angeles, 1930, p. 239. 21:1 Compt. Rend. Off. du Premier Cong. Internatl des Recherches Psychiques, 1932, pp. 396-408. 22:1 In the interest of completeness perhaps I should mention Dr. Troland's short study of telepathy made at Harvard in 1916-1917, including only 605 trials with a probability of ½. It has no significance whatever and was too small a series to be important. There was also the negative report of an examination by Prof. Stratton of a man who claimed telepathic powers and who invited the inquiry. (The control of another person by obscure signs, Psych. Rev. 28: pp. 301-334, 1921.) One can readily see that Prof Stratton might have been right in his conclusion of sensory following of signals, but might equally well have been wrongin having provided conditions unfavorable for abstraction, as I can see now was the case. The "internal" field is even more important than the outer in psychological experimentation. 23:1 Bechterew, W. Zeitschrift f. Psycho-Therapie, 8: pp. 280-304, 1924. 23:2 Rhine, J. B. and Louisa E., Jour. Abn. and Soc. Psy., 23: pp. 449-466, 1929; and 24: pp. 289-292, 1929. 23:3 The Eberfeld horses were doubtless best known among these. Krall was convinced that his horses were capable of telepathy but the demonstration of it has remained too debatable for definite conviction. Krall's own report in 1927 (Ztschft f. Parapsychol. 21: pp. 150-153) entitled "Denkbüertragung Zwischen Mensch and Tier", lacks too much in completeness and detail to permit a safe judgment. 23:4 Annal. Sci. Psych., XX: pp. 14-21, and pp. 40-53, 1910. 23:5 Proc. S.P.R., XX I: pp. 60-93, 1907; XXVII: pp. 279-317, 1914. 24:1 Proc. S.P.R., XXXI: pp. 124-217, 1920. 24:2 S. G. Soal, Proc. S.P.R., XL, 1932, p. 168. Dr. W. F. Prince was very noncommittal in his review, p. 21, B.S.P.R., Bulletin VI, which I take as also an indication of the inconclusiveness of the experiment. 24:3 Proc. S.P.R., 38: pp. 1-9, 1928. 24:4 Proc. S.P.R., XL, pp. 165-362, 1932. 24:5 Die Emanation der psycho-physischen Energie. (Munich) 1908. 24:6 Expmtl. Untersuchungen auf dem Gebiete des räumlichen Hellsehens (Munich) 1909. 24:7 Telepathie and Hellsehen. (Halle) 1921. 26:1 Proc. S.P.R., VI: pp. 66-83, 1889. 26:2 Proc. S.P.R., VII: pp. 199-220; pp. 370-373. 26:3 Proc. S.P.R., XXXVIII: pp. 223-271, 1928. 27:1 Proc. S.P.R., XXXIX: pp. 375-414, 1931. 28:1 Proc. S.P.R., XXXI: p. 377, 1921. 28:2 Tischner, loc. cit., p. 206. 29:1 Proc. S.P.R., XII: p. 352, 1897. 29:2 This mention is based on Tischner's review, op. cit., p. 206. 29:3 Proc. S.P.R., XXX: pp. 251-260, 1920. 30:1 Life after Death, E. P. Dutton, New York, 1918; pp. 137-142 30:2 Op. cit., p. 211. 30:3 Jour. fur Psychol. and Neurol., 1918. 31:1 Notre Sixieme Sens, Editions Montaigne. Paris, 1928.
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Footnotes