Duke Experimenters

This article was collectively written by J. B. Rhine (Professor of Psychology), J. G. Pratt (Instructor in Psychology), Charles E. Stuart (Prince Memorial Fellow), Burke M. Smith (Graduate Research Assistant) and Joseph A. Greenwood (Assistant Professor of Mathematics) of the Parapsychology Laboratory Department of Psychology at Duke University. It appeared in "Extra-Sensory Perception After Sixty Years: A Critical Appraisal of the Research in Extra-Sensory Perception" (1940, Henry Holt and Company, New York).

Physical Relations of ESP

Range of Stimulus | Physical Features of the Stimulus | Spatial Relations and Success in ESP Tests | Temporal Conditions and Success in ESP Tests | Summary

- J. B. Rhine, J. G. Pratt, C. E. Stuart, B. M. Smith and J. A. Greenwood -

          THE PHYSICAL universe is much more easily measured than the world of mental process, and this enables the inquiry concerning the physical relations of ESP to be made somewhat more successfully than have been the psychological relations. The general trend of evidence on the question of physical relationship is, however, for the most part distinctly negative; that is, toward an absence of any effective relationship. It is important, nevertheless, to know these facts even though they fail to furnish the quicker and simpler explanations that readily discovered positive relations might afford.

It is not yet demonstrated that there is any determinable quantitative connection obtaining between ESP and the physical world (e.g., any equivalent in ESP to Weber's Law for sense perception). However, with present knowledge of the universe, it seems most logical to follow as long as possible the working hypothesis that there is some physical stimulus behind every ESP performance and that the card and the agent's experience relate to the percipient's response in some physical manner, however unknown its nature or its medium. It is difficult, indeed, to see how this supposition can be escaped so long as it is necessary to identify an object in its spatial and temporal framework and characterize it in terms of the physical system.

In reviewing the possible relations between ESP and the physical world, there are three general headings that may be followed. First, the physical nature of the stimulus; second, the spatial conditions of the tests; and third, temporal relations between stimulus and percipient. With the exception of the last named of these three topics, this will be largely a review of items and relations that have already entered into the discussion in the preceding chapters. They may therefore be given only brief summary at this point.

Range of Stimulus [top]

Pure Telepathy (PT). Almost from the very beginning of the experimental period of the history of extra-sensory perception, the supposed capacities of telepathy and clairvoyance have been differentiated under one name or another. Over the period taken as a whole, it is probable that about half of the experimental reports were intended as investigations of telepathy and the rest as investigations of clairvoyance. But although the two phenomena were generally regarded as belonging to different categories, most of the research in extra-sensory perception has not been primarily concerned with the discovery of ESP relations; it was devoted to the investigation of the ESP hypothesis itself. For instance, in the investigation of telepathy up to 1934, there were only two instances(1, 2) in which the possibility of clairvoyance was excluded, and these were short, non-quantitative series.

(1) Shield, Mrs. M. E. "Experiments in Thought-Transference," Journal of the SPR, III (1887), 179-182.
(2) Wiltse, A. S. "Experiments in Thought-Transference," Journal of the SPR, VII (1896), 197-206.

In 1934 Rhine(3) reported the results of experiments designed to isolate telepathy from possible clairvoyance, calling the tests "pure telepathy tests." In these experiments the agent made a purely subjective "random" selection of symbols and did not record the selection until after the time for the recording of the subject's call was past. There was no objective stimulus at the time aside from the accompanying bodily changes of the agent. So far as the logic of the experiment goes, unless it be supposed that precognition(4) might enter in to anticipate the agent's recording of the symbols he selects, this method should give a sound test of the telepathy hypothesis.

(3) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.
(4) For the present, however, it cannot be said that precognition is excluded experimentally, and indeed this may be a difficult task to achieve. But it is an alternative that few psychologists will at present take. Perhaps by the time this situation alters, better tests will be available. The further point is appropriate, namely that, as will be seen below, ESP is voluntarily controlled: this means that if it is directed toward the agent, there is some reason to suppose it is not directed toward the (future) written record.

On the score of experimental adequacy, only the Rhine(5) long-distance pure telepathy series already discussed in Chapter VI fully meets the requirements, but there is enough confirmatory work conducted under more ordinary conditions to give to the case for pure telepathy the status of established, especially since telepathy seems to be regarded on a priori grounds as somewhat less improbable than clairvoyance.

(5) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.

A supporting series contributing to the case for pure telepathy may be drawn from the monograph by Rhine(5) in the work of Stuart with subject H. P. In the total of 78 runs of this series, 59 runs were conducted with subject and experimenter in different (sometimes adjoining) rooms with connecting door open but out of line of vision. The results were significant either when taken as a whole or when that portion is considered which was done with the participants separated. There is also a report by Pegram(6) describing a comparative study of the three test conditions: PC, PT, and GESP. Pegram gave a series of 165 runs for each of the three conditions to a group of children and adolescents - most of them blind. Forty runs of the 165 were given with agent and percipient in separate rooms with a one-way signal. The total PT average was 5.61, which is statistically significant. The 40 runs in separate rooms gave an average of 6.1, likewise significant.

(6) Pegram, Margaret H. "A Comparison of Telepathy, Clairvoyance, and General Extra-Sensory Perception." [Unpublished MS].

Pure Clairvoyance. By far the greater amount of the ESP research has been conducted with the use of clairvoyance tests, largely because these tests require simpler controls and precautions. Since this work contains also most of the experimentation conducted under more advanced precautions, the case for clairvoyance rests upon much stronger evidence in point of quantity and variety than does that for pure telepathy. Four of the six main cases cited in Chapter VI as meeting all of the counter-hypotheses were tests for pure clairvoyance (one was pure telepathy, and the sixth - that of Riess - was done under GESP conditions). There is, of course, a great deal of confirmatory data supporting the case for pure clairvoyance, but there is obviously no need to attempt to enumerate the supporting series to bring this into a classification of established(7).

(7) There is again, however, the alternative hypothesis involving precognition as a possibility. That is, the subject may be supposed in the clairvoyance tests to be apprehending the symbols not directly from the cards but by way of the future visual perception of the cards by the experimenter as he looks at them in the act of recording. This alternative hypothesis would be one of precognitive telepathy, corresponding to the alternative in the pure telepathy case of precognitive clairvoyance. The answer to the precognitive telepathy hypothesis is much the same. It will certainly not be preferred by critical students today, although it must be recognized as a possibility. The argument, too, from the voluntary control of ESP applies here. If the subject thinks he is calling a card, it is difficult to suppose that he is actually aiming instead to apprehend what the agent will be experiencing at some future time-difficult, though not impossible.

PC and PT Compared. There appeared in the report by Rhine(8) in 1934 the work of nine subjects who participated in PC and PT experiments with sufficient similarity of conditions to permit rough comparison. Most of this work belongs to the period of exploration with fewer precautionary measures in use than is at present the case. At the time of the publication of that monograph, seven of the nine subjects averaged, in 11,700 trials in PC tests, 8.1 hits per 25; while in 7,975 PT trials, the average was 7.9. A footnote mentions an eighth subject who later completed a comparative series, averaging 8.0 on clairvoyance and 8.8 on telepathy. The ninth subject(9) was an exception. This was the medium, Mrs. G., who averaged, in 11,900 trials for PC, 5.6 hits per 25. while in 4,100 trials for PT the average was 8.4. In this case, however, there was expressed by the subject at the beginning of the series a strong preference for the PT tests and a strong antipathy for the cards. This is the only instance of such strong preference, and the only instance of so striking a difference in average scoring.

(8) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.
(9) 243 Rhine, J. B. "Telepathy and Clairvoyance in the Normal and Trance States of a 'Medium'," Character and Personality, II (1934), 91-111.

Rhine also presents evidence of daily trends in rise and fall of score averages that are similar for both PC and PT in the same subject. Similar effects from drugs, fatigue, and tonsillitis are also mentioned.

The work of Pegram(10), referred to above, in which comparison was made of PC, PT, and GESP, reports, for the PC average, 5.10 per 25 for 165 runs. As already mentioned, the average score for a similar number of runs for PT was 5.61. In this work, however, there was the different feature that the subject did not know under which condition he was working in any given run. The purely speculative suggestion might be offered that under such conditions the tendency of the children would be to focus upon the agent more than upon the cards. The difference in intrinsic interest should favor such orientation.

(10) Pegram, Margaret H. "A Comparison of Telepathy, Clairvoyance, and General Extra-Sensory Perception." [Unpublished MS].

Taken as a whole, such comparative work as there is on the two distinct experimental procedures, PT and PC, warrants the tentative position that PT and PC results may have the same general controlling factor (or condition). In view of the fact that so many of the same subjects were found to be able to perform successfully in both types of tests, and a number of conditions appear to affect both experiments in a similar way, it might be said tentatively that the hypothetical relation of a common controlling factor (or condition) is indicated.

General Extra-Sensory Perception. It has already been made clear that most of the earlier experimentation in the field of ESP was done under conditions that allowed both telepathy and clairvoyance to occur even though the tests were called telepathy tests. It is now customary to call this condition the general ESP condition or GESP. Since 1934, a relatively small amount of experimentation has been done under that condition, mainly because of the greater difficulty of controlling and safeguarding the experiments from the point of view of auditory cues. Only one of the series summarized in Chapter VI as meeting all of the counterhypotheses is of the GESP type; namely, the work of Riess.

There is no question as to whether success under the GESP condition is an established matter. The fact that either telepathy or clairvoyance might be supposed to occur under the test conditions is sufficient evidence to establish the case for a condition which permits both. The question does present itself, however, as to whether the GESP condition is more favorable to high scoring than PC or PT. Do telepathy and clairvoyance supplement each other? This is a question of both practical and theoretical importance. Practically, it is worth while to determine whether GESP is a more favorable condition for ESP experimentation than either PC or PT. Theoretically, the question is important for the bearing its answer may have upon the question of the relation of PC and PT results; that is, reasoning from the sensory analogy, if telepathy and clairvoyance are independent processes, they might be expected to supplement each other and insure greater success under GESP conditions. On the other hand PC and PT successes are basically reliant upon the same process, one that simply adapts itself to widely separated types of stimuli, there is less reason, if indeed any at all, to expect any superiority of GESP performance over that of
PC and PT.

GESP, PT, and PC. The results for the GESP tests, in spite of the great number of trials made under such conditions, are not entirely unambiguous in their bearing on this question. There is, however, enough work in the same general direction to warrant the statement that it is indicated that the GESP condition is not better than PC or PT; that is, so far as these tests have been developed in the past.

First, there is a general impression to be had by a comparison of the GESP work as a whole and the PC work (the PT tests were relatively few in number and will be included hereafter with PC). A general inspection of the assembled published reports as given in Table 29, will indicate that on the whole - Riess's work excepted - the GESP performance was not particularly outstanding. The difficulties of such a general comparison inhering because of the different p-values may be overcome by stating the subject's ESP performance in terms of the ESP quotient. Table 18, gives the ESP quotient for all work which had been conducted with given p-values. It happens that most of the trials with p = 1/5 are PC tests and most of the rest are GESP. Section I of the table includes only p-values which were used to the extent of 10,000 trials. It will be seen that the results with p = 1/5 - that is, the PC work(11) - gave the highest ESP quotient. This result may not be interpreted as showing that PC is superior to GESP. These results are ambiguous since it is impossible to estimate what advantage may lie in the p-value of 1/5. But it can be inferred that GESP is not sufficiently superior to PC to overcome any such advantage.

(11) Omitting the Riess series (GESP) does not change the quotient by as much as a tenth. Hence, the designation of the (p = 1/5) block as PC is safe.

Turning to more specific comparisons, the work of subject A.J.L. reported by Rhine(12) may be mentioned in this connection. This subject averaged 9.9 in 360 trials of GESP and made the same average in 240 trials of pure clairvoyance for the same experimental period. On p. 74 of the same report, subject HP is credited with 300 trials of clairvoyance averaging 8.3 and the same number of trials in GESP tests averaging 9.7. The subject in this case did not know when the shift was made from one condition to the other; the tests were made with the cards and the experimenter screened from view. The difference is not significant. Gibson found, in his study of comparative methods, that the work of eleven subjects averaged on the GESP technique at a point below OM and above BM and DT. In Price's report, summarizing the work of Price and Pegram on the blind, Table VIII showed that of eight classifications - BT, GESP, OM, and BM - appearing twice under two different conditions, open and enclosed cards, GESP ranks second and fourth in score averages. In the paper by Pegram, referred to above, in which a comparative study was made of PT, PC, and GESP conditions, 165 runs being given for each of the three conditions, GESP averaged between PC and PT. The averages for PC, GESP, and PT are as follows: 5.10, 5.25, 5.61.

(12) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.

There is, however, the apparently exceptional case of MacFarland in which a comparison of GESP and DT was made consisting of 612 runs for each. Two experimenters were involved and each experimenter found that GESP averaged above DT and the total difference was significant. The average for GESP was 5.71 and for DT, 5.25. But DT is not a comparable PC technique; BT is necessary for such comparison. If correction is made for the fact that of all the PC methods DT averages in general are comparatively low, the comparison is considerably different and this case does not constitute a contradiction(13).

(13) Actually, if the results obtained from BT and DT in the comparative studies of Rhine (238) and Gibson with the same subjects are taken as a basis of comparison, we find that the deviation on the BT method averages 3.3 times as high as that of DT. Multiplying the MacFarland DT deviation of .25 by this correction necessary to give a figure comparable to GESP, we get 5.83 which compares very favorably with the 5.71 for GESP.

The fact that the Riess A series, which gives the highest average (18.24 for 74 runs) for any series ever reported, was conducted under the GESP condition suggests, of course, that the high average might have been due to the GESP condition itself. Lack of any control, however, does not permit a conclusion of this nature. The most obvious interpretation would be that the high score average was a matter of individual difference, since individual differences are apparently the most conspicuous source of differences in results at the present state of the research. If there were another GESP series which stood out comparably in all the long history of GESP test procedure, the case might be put more favorably. As it is, there is no experimentally warranted ground for ascribing advantage to the GESP condition unless the individual subject has a strong preference or belief which favors that particular method and condition. It may be said, then, that the hypothesis that GESP is essentially not more efficient than PC or PT is indicated.

On the strength of this conclusion and rating it is suggested that the PC and PT tests are measuring a single capacity, a mode of perception which has a range of apprehension that includes in its scope both objects and the experiences of other persons.

Responses to Complex Stimuli. Obviously a single object can be perceived, as can also the mental states or experiences of another person. But can the normally successful subject also respond with better-than-chance success to a pair of objects or to a relation between two or more events? That this is the case may be stated at the outset as an established fact. However, as to how far this apprehension of relations can go into advancing orders of complexity is a question that only points the way to still further research.

Both the DT and BM procedures, as well as the ESP shuffle or pack matching tests and the pre-shuffle card calling tests, clearly involve a response on the part of the subject to two or more objectively separable events or things which are not apprehended unless by ESP. In the simplest of these complex relations, the BM procedure, an unknown card is successfully matched opposite an unknown key card. The same is true of STM work when the symbols of the key cards are concealed from the subject. In the last 10,000 of the 60,000 trials reported by Pratt and Woodruff, this was the case. In the work reported by Pratt(14), the keys were covered; this was also the case in the Pratt-Price work and in a significant section of that reported by Stuart(15).

(14) Pratt, J. G. "Clairvoyant Blind Matching," Journal of Parapsychology, I (1937), 10-17.
(15) Stuart, Charles E. "The Effect of Rate of Movement in Card Matching Tests of Extra-Sensory Perception," Journal of Parapsychology, II (1938), 171-183.

In the typical DT experiment, the localization of the card that is to be called-that is, actual physical localization of it - would have to be other than sensory. The subject does not look closely at the pack to follow the edges of the cards from the side (even if he did, he could not hope to identify the actual cards by location in the deck). In screened DT, the case is clearer still. In the screened series, then, of Murphy and Taves, Martin and Stribic, MacFarland and George, and DT work by others, it may be supposed that the subject was responding to the combination of symbol and position in the deck. Whether or not he first located the card and then attempted to identify the symbol is a question in itself. That his performance involves somehow a relation of position and symbol can hardly be questioned.

Again, when the subject attempts to match a deck of cards against another or against a series of card symbols by so shuffling the deck as to make the decks match with a more than chance frequency, if he is not sensorially aware of the position of the cards in the deck he is shuffling, and if the target deck or target series of symbol records is screened from view., it would appear that a still more complex situation obtains. The degree of complexity involved will probably have to be determined by further and more analytic tests. The same is true for the pre-shuffle card calling in what is termed "precognition tests" in which the subject attempts to call the order of a pack of cards as it will be after it has been shuffled by the experimenter.

Fine Discrimination in Location. It is established also that discrimination of symbols is possible even when they are confined to the space of twenty-five cards to the quarter inch as would be the case with the DT and ESP shuffle tests (see 16, 17, 18). Success under these conditions implies various kinds of discrimination: (a) in locating the individual cards; (b) the perceptual disentangling of the proper symbols from the group of twenty-five which are all in close proximity to. each other; and (c) there being several of each symbol probably adds further to the difficulty of discrimination. The radiation or transmission patterns of all twenty-five symbols should have approximately equal stimulus value, all superimposed upon each other. There seems, however, to be no physical handicap inherent in the close proximity of the cards to each other during the tests. It is true the DT scores have not been as high as the BT scores made with the same subjects under the same experimenters (see Table 20). But this is very plausibly explained as a mental rather than a physical phenomenon; that is, psychologically, it would be expected that better orientation of the subject to the cards is possible toward either end of the run. Were it a physical limitation, there is no reason why the bottom of the inverted pack should be a region of successful scoring(19).

(16) MacFarland, J. D. and George, R. W. "Extra-Sensory Perception of Normal and Distorted Symbols," Journal of Parapsychology, I (1937), 93-101.
(17) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.
(18) Rhine, J. B., Smith, B. M., and Woodruff, J. L. "Experiments Bearing on the Precognition Hypothesis: II. The Role of ESP in the Shuffling of Cards," Journal of Parapsychology, II (1938), 119-131.
(19) Similar curves have been obtained in a number of investigations since the work of Ebbinghaus In the recall of nonsense syllables. In a way similar to the DT test, the difficulty of identification would seem to be increased as the item is remote from either end of a run.

Also, success in calling cards at distances, measured in hundreds of yards and upward, implies fine discrimination in location. This is true in particular when the right card is picked out from the many similar cards which lie nearby.

Physical Features of the Stimulus [top]

Objective Invisibility of Stimulus. It seems to make no difference whether or not, at the time of the test, the stimulus is being looked at by another person or whether it is even exposed to light and potentially visible; that is, as has been mentioned above, a card at the bottom of the deck is apprehended as well as one at the top. One that is inverted may be perceived as successfully as one that is (of course, out of view of the subject) exposed to the light (see again the comparison of PC and GESP for this point; see also tests with opaque envelopes (20)). This may be regarded as an established condition, yet these are not positive relations of the physical condition of the stimulus to success; they are negative ones (the absence of relation), indicating that the physical condition in question is not important.

(20) Rhine, J. B. "ESP Tests with Enclosed Cards," Journal of Parapsychology, II (1938), 199-216.

Size of Stimulus. It is established that ESP occurs with the use of test symbols within a size range of 1/16 to 3 1/2 inches. This is to say, in other words, that physical size is not determinative of success in the tests and that there appears to be no physical relation in this connection within the limits tested. First, L. E. Rhine compared cards (see Fig. 6, below) on which several symbols were printed with cards which had but one symbol with a view to ascertaining if the greater. number of stimuli on the cards facilitated the apprehension of the symbol. There was no significant difference found, between these and the controls. Among the various sizes of symbols used by Pratt and Woodruff were symbols given extra width, thus setting off the symbol against the white background by a greater contrast. These heavier symbols stood out more definitely in visual perception, yet they were no better than the others except for the period of novelty which was, for all sizes of symbols, outstanding in score average.

Photographs of ESP Cards used in Various Experiments

Upper: Regular ESP Cards
Middle: Distorted symbols used by MacFarland and George.
Lower left: Variations in symbols size and multiple symbol cards used by L. E. Rhine.
Lower right: Steps in sealing cards in opaque envelopes for enclosed card experiments.

Distorted Symbols. MacFarland and George introduced badly distorted symbols (see Fig. 6, above) in comparison with the normal, anticipating that the weak and erratic mode of perception in the ESP tests might be supposed to miss the distorted symbols more often than the normal. There was also the possibility that the distorted symbols. would arouse esthetic avoidance in the subject. No appreciable difference was found, however, except when the experimenter himself, MacFarland, acted as subject. It is indicated that grossly distorting the symbols does not reduce their perceptibility.

Spatial Relations and Success in ESP Tests [top]

Under this heading, there are three relationships that may be said to be established.

Angle of Card. First, the angle of the stimulus cards is not related to success. This would be important for a radiation or transmission theory of ESP. If the symbol is in line with the subject's line of vision - that is, with the edge straight toward him - he presumably could not see what is on the card even if it is not in any way screened. This is easily understandable, since the only part of the card that could reflect light or exercise differential absorption of light and make itself visible to him is the edge turned toward him. Now if any radiant energy were emanating from the card or were transmitted from behind it and differentially absorbed by it, no matter what type of energy were supposed, it could transmit at the most the thin line of the side view of the card and of the symbol itself. The only difference in the symbols, then, would be their length, the length of a single line.

In the Pearce-Pratt series(21), as has been stated, the cards and subject were on approximately the same level in different buildings. In the Warner series(22), the angle of the card with the line between the card and the percipient was roughly between 30 and 60 degrees. In tests with A. J. L., Rhine(23) held the cards in almost every conceivable angle with relation to the subject. In other tests, the angle of the cards has varied somewhere between zero and ninety degrees, with apparently no favored position being discovered.

(21) 242 Rhine, J. B. "Some Selected Experiments in Extra-Sensory Perception," Journal of Abnormal and Social Psychology, XXXI (1936), 216-228. See also Journal of Parapsychology, I (1937), 70-80.
(22) Warner, Lucien. "A Test Case," Journal of Parapsychology, I (1937), 234-238.
(23) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.

Screens as Barriers. Second, no screens thus far used in the ESP research have proved to constitute a real barrier to the apprehension of the stimulus objects. Most of the screens used have been introduced in the interest of excluding vision of the object. There has been little systematic attempt to institute screens designed to bar out different forms and frequencies of energy. In view of the results obtained under other physical conditions, experimenters have not regarded such a step as warranted. That is, it has become evident that the known energies against which screens could be raised are not at work in the ESP performance.

The screens used have been for the most part of common building materials: of wood, usually three-ply; of artificial board; and other convenient opaque materials. When subject and agent or cards are placed in different rooms or different buildings, there are, of course, interposed walls of tile, plaster, stone, brick, and other materials. In the instance of the Pearce-Pratt study, there were four stone walls in direct line between cards and percipient. In the Riess series, buildings, as well as a hill, intervened between agent and percipient. In the long distance pure telepathy series, the mountainous nature of the intervening country laid miles of the earth's crust in direct line between agent and percipient. It is obvious that any energy which could intermediate under such conditions would have to be one capable of penetration greater than any radiation at present known or else would have to be capable of reflection. The energy that would satisfy the requirements here would have to be one capable of conveying patterns as small as ESP cards and at the same time able to transmit the mental experiences of an agent. The transmission of unknown card symbols would, if radiant energy were supposed to be involved, require a wave length of the order of light waves or shorter instead of the greater length used in radio transmission. It may be said, then, that not only have the screens or interposed barriers been no real limitation upon ESP performance, but they have incidentally covered the needs for physical exclusion of the known energies which might he supposed to intermediate between the percipient and the object or agent.

Distance. Third, distance is itself in effect a barrier to certain physical energies and it, too, is apparently not related to the ESP performance; at least, not in any direct manner. This is not to say that it has no psychological consequences, since the common supposition that distance (or anything else) limits perception may seriously affect the subject's belief and confidence and thus indirectly affect the results.

That ESP occurs with considerable distance interposed has been indicated in some of the earlier ESP reports. Janet's hypnotization at a distance, the long-distance tests of Usher and Burt, and those of Sinclair all justify the argument of disposing of distance as an effective factor. Rhine(23) pointed to the fact that when subjects were tested at a distance they frequently did better than at close range, and he attributed the effect to the possibly better abstraction by the subject in the absence of the stimuli. It might be speculatively added that the greater challenge too might have had some weight. The outstanding series of distance performances have been often mentioned. The Pearce-Pratt series at 100 and 250 yards and the long distance pure telepathy series are most outstanding. The Riess series involved a distance of a quarter mile. Rhine summarizes(24) other work not in itself outstanding, but significant if taken as a whole. By analyzing score averages in connection with the different distances involved, it is shown that there is no relation whatever found between distance and ESP success. The distances involved in the work summarized extend to over 2,000 miles.

(24) Rhine, J. B. "The Effect of Distance in ESP Tests," Journal of Parapsychology, I (1937), 172-184.

Is a Physical Hypothesis of ESP Tenable? From the physical point of view, the evidence of pure telepathy and the evidence of pure clairvoyance with its range of stimuli, the data on size of stimulus, and on the several other physical aspects outlined above present a situation that no physical energy can meet as far as the scope of present knowledge extends. It may be, as was suggested above, that if there were adequate grounds for accepting the precognition hypothesis, this might offer a convenient escape from having to accept these two apparently widely different orders of stimuli (that is, object and mental images) and still further reduce the difference between PC and PT. However, until such a solution is found, the physical problem of accounting for the perception of two such divergent orders of phenomena as physical objects and human experiences remains.

Following the discussion of the experimental findings, some rational consideration of the above relations is now justified. It is, as mentioned above, a logical necessity to search diligently for possible physical causes of ESP and to discover any quantitative relation there may be. It is equally logical, however, and equally necessary to be open to any other possibilities; discovery often comes from simply escaping the bondage of logical deductions based on irrelevant analogies.

In summarizing the studies relating ESP to the physical world, it may be said that a physical hypothesis of the ESP stimulus has to account first for pure telepathy and pure clairvoyance, stimulus range and size differences, and variations of angles of the symbols that have been demonstrated. It must transmit or radiate patterns of very small size and yet possess a high degree of penetration and be discriminable when the stimuli are crowded together in the space of one hundredth of an inch. Finally, the hypothesis must account for the fact that distance is apparently not related to the degree of success. If one set of data could be taken alone, there would be perhaps some possibility of finding some hypothetical extension of the present array of physical energies, but when the hypothesis has to meet the diverse phenomena described above, the case is very different.

Taking these requirements together, it does not seem possible to apply any present physical hypothesis to the results as a whole. As a matter of fact, no one has as yet been able to formulate even an untested hypothesis that consistently accounts for the results as a whole and still adheres to the present outlines of physical knowledge. Taking one aspect of the general requirement, Lemmon(25) suggested that Lewis's virtual contact theory might be adapted to cover the ESP results. This theory is based upon a type of geometry which Lemmon indicates would allow any agent or percipient to be in virtual contact regardless of distance. But there is, first of all, the grave difficulty for this hypothesis that it has not been established as applicable to the physical world as known; that is to say, it is not a physical law which might be used as an hypothesis for ESP. But even supposing that it were a physical law, the other conditions besides distance which the theory would have to meet would still remain. When, for instance, Lemmon undertakes to meet the requirements for an energetics of ESP, he very evidently has difficulty, and in fact offers no hypothesis of intermediation at all(26).

(25) Lemmon, V. W. "Extra-Sensory Perception," Journal of Parapsychology, IV (1937), 227-238.
(26) In correspondence, however, Dr. Lemmon indicates that he is giving this matter further thought and has an hypothesis in mind.

It need hardly be said that the results of the ESP tests, fragmentary though they be, bring the investigation to the frontiers of physics itself. In the present stage of the research, there is no way to determine whether it will be necessary to assume an order of energetics not yet recognized, or whether it will be better to assume an order of perception independent of energetic stimulation.

Rhine suggested in 1934 (27, p. 122) that for the sake of coherence some conception of energetic relation basic to ESP performance was necessary but thought that in view of the evidence it could not be radiant energy as known today. At the same time (27, pp. 143-145), he suggested that some form of a "capacity-to-escape-material-conditions" hypothesis was warranted by the results. These two views were not presented as contradictory. The aim was to focus the difficulty in the smallest possible area; namely, the question whether materialistic conceptions, mechanical laws, are applicable, and very evidently they are not.

(27) Rhine, J. B. Extra-Sensory Perception. Boston: Bruce Humphries, 1934.

The hypotheses available, then, at this juncture might be stated as follows: First, advancing physics will find principles of explanation now unknown which will account for the phenomena of perception shown in these results. This will keep the stimulation aspect of ESP within the realm of physics as is true of sensory perception. Second, a mode of perception occurs that is without a basis of physical stimulation, not merely perception without the exercise of the recognized senses but perception without objective stimulation of any kind as the term is now regarded. No choice is, of course, possible for the present between these hypotheses, and none is necessary since both indicate merely directions of exploration for the related sciences.

Temporal Conditions and Success in ESP Tests [top]

A final topic remains under the heading of possible physical relations, perhaps the most obscure of all. This is the question of ESP and temporal conditions: Is the actual coincidental existence of the object essential to ESP experience of it? It was pointed out in a previous chapter that so far as the spontaneous parapsychic experiences go, a large portion involve a cognition of future events. The first comprehensive and systematic attack on this question began in the Duke Parapsychology Laboratory in the fall of '33 and is still continuing. Reports of results of possible bearing upon the question were made by Carington(28) and Tyrrell(29) in '35 and '36 respectively. Two reports, preliminary in character and tentative in conclusion, were issued from the Duke Laboratory in '38, the first by Rhine(30) and the second by Rhine, Smith, and Woodruff. No conclusion was published in either paper attempting to establish a claim of the occurrence of precognition, or ESP of future events.

(28) Carington, W. W. "Preliminary Experiments in Precognitive Guessing," Journal of the SPR, XXIX (1935), 86-104.
(29) Tyrrell, G. N. M. "Further Research in Extra-Sensory Perception," Proceedings of the SPR, XLIV (1936), 99-168.
(30) Rhine, J. B. "Experiments Bearing on the Precognition Hypothesis," Journal of Parapsychology, II (1938), 38-54.

The work of Carington, involving the attempt of precognition of thrown dice, is inconclusive on statistical and other grounds, though it is suggestive in character. The results of Tyrrell, obtained with an electrical machine, would appear to be attributable to precognition unless it be supposed either that the working of the machine might he sufficiently apprehended by ESP as not to require actual future reference or (which is perhaps a stronger though still unlikely counter-hypothesis) that the habit pattern of the experimenter coincided (in spite of the commutator used) with habit patterns of the subject. Tyrrell's findings are at least challenging, 'as, it may be added, are those Rhine obtained with pre-shuffle card calling (i.e., prediction of the order of a deck of cards as it will be after shuffling by the experimenter). However, evidence of the possibility of successfully matching a given order of symbols or another deck by the shuffling itself was contributed by Rhine, Smith, and Woodruff, and this finding was recognized to be, and was presented as, a possible counter-hypothesis. Accordingly, the pre-shuffle card calling results were regarded as ambiguous, perhaps due to precognition and perhaps due to the unintended use of ESP in the shuffling of the deck by the experimenter. This is not to say, however, that the possible ESP shuffle effect actually was shown to have (or was believed to have) occurred in the pre-shuffle card calling series. On the contrary, there is some evidence that it did not. But on so important an hypothesis as that of the apprehension of future events through ESP, no alternative possibilities can be overlooked. Accordingly, so far as published work is concerned, the question of time relation in ESP remains experimentally no stronger than the work just summarized.

Elsewhere it has been suggested by Rhine(31) that the absence of any positive relation found so far between ESP and the spatial framework argues that ESP is also independent of time, since time and space are inseparable the one measurable only with relation to the other. It was stated, too, that unusual spontaneous experiences which suggested the ESP research show a large percentage of instances of apparent precognition. If such spontaneous experiences are borne out in their clairvoyant and telepathic features, it adds to the seriousness with which we must regard the previsionary aspect. The hypothesis is not one that can be settled by logic or by appeal to spontaneous experiences; it will be difficult enough by experiment. But the question is a legitimate one, and it has had an encouraging beginning in experimentation. Its potential importance may be gauged by the extreme reconstruction of scientific cosmology which a positive finding would demand. Such revolutions have invariably been beneficent in the long run.

(31) Rhine, J. B. New Frontiers of the Mind. New York: Farrar and Rhinehart, 1937.

Summary [top]

1. General extra-sensory perception, telepathy (PT) and clairvoyance (PC) are established.

2. It is indicated that PC and PT are subject to the same general controlling factor or condition.

3. GESP may be stated as indicated in having no marked superiority as an experimental procedure to PC or PT.

4. It is established that in the ESP tests the subject may, under certain conditions, respond significantly to more than one object; that is, to a relation between two or more objects.

5. The discrimination of stimulus cards in a pack of twenty-five similar cards, one hundred to the inch, is established as possible by means of ESP.

6. Objective invisibility of the stimulus offers no barrier.

7. Within the range examined, size of stimulus is unimportant.

8. It is indicated that grossly distorting the symbols does not reduce their perceptibility.

9. The angle at which the stimulus card is held is not of consequence.

10. Such obstructions as have intervened between object and percipient have in no instance appeared to interfere with ESP.

11. Distance is not found to have any effect.

12. Finally, it must be concluded that no positive physical relations of limiting character have been found up to the present time, and no known energy can be offered as the hypothetical intermediating causal link between stimulus and percipient.


The article above appeared in "Extra-Sensory Perception After Sixty Years: A Critical Appraisal of the Research in Extra-Sensory Perception" (1940, Henry Holt and Company, New York) by J. B. Rhine, J. G. Pratt, C. E. Stuart, B. M. Smith and J. A. Greenwood.

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