Are ESP and PK aspects of a unitary phenomenon? A preliminary test of the relationship between ESP and PK

Journal of Parapsychology, The, Fall, 2003 by Chris A. Roe, Russell Davey, Paul Stevens

Gertrude Schmeidler (1988) posed the question: "Is it proper to use psi as a general term for ESP and PK? If it is--if they are alike enough to be classed together--as there any need for the separate terms?" (p. 172). Her question makes explicit an assumption that underlies much of the work in parapsychology, albeit rarely stated, that psi is an intrinsically unitary domain within which ESP and PK are complementary expressions of an inherently undifferentiable and integral set of processes (see also Irwin, 1985, p. 44; Thalbourne, in press).

However, few attempts have been made to test this assumption, and most evidence that bears on the question (some of which we overview below) is circumstantial. Given this ambiguity, theorists have been free to adopt a range of positions vis-a-vis the relation between these two phenomena, depending on one's preferred ontology (see Storm & Thalbourne, 2000). These positions range from assuming ESP and PK to be unitary with neither primary (Schmeidler, 1994b), unitary with PK as the basic phenomenon (attributed by Schmeidler, 1994b, p. 229, to Helmut Schmidt), or unitary with ESP the basic phenomenon (as captured for example in decision augmentation theory (DAT) (1): see, e.g., May, Utts, & Spottiswoode, 1995), through to a view associated with William Braud (e.g., Braud, 1985) that sees ESP and PK as complementary phenomena that have quite distinct characteristics and thrive under differing conditions.

This latter position is more in keeping with the view of the general public, who seem to draw a sharp distinction between ESP and PK, regarding the former as much more likely and much more conceivable than the latter (see, e.g., Broughton, 1991, p. 35; Schmeidler, 1988, p. 175). For example, Louisa Rhine (1963, p. 88, cited in Irwin, 1999, p. 127) reported that although she had over 10,000 reports of ostensible ESP, only 178 cases of PK were on file.

Similarly, if one takes an operational definition, then one may come to regard the two as clearly distinct, because ESP is measured in terms of a participant's response that is then compared with a target, whereas PK is measured in terms of physical change in some system in accordance with the participant's intention or aim. However, such operational definitions may say more about the method of testing than about essential features of the phenomenon, and there is typically still sufficient scope for one to class a phenomenon as an instance of ESP or PK (or both) according to one's preference (see Thalbourne, in press). Ultimately, there is yet no reliable insight into the relationship between ESP and PK.

PRIMA FACIE EVIDENCE THAT BEARS ON A COMPARISON OF ESP AND PK FUNCTIONING

There is some anecdotal evidence to suggest that ESP and PK abilities are related, as some exceptional individuals who have shown impressive ability in one domain have also performed well in the other, such as Matthew Manning (Schmeidler, 1988) and Eileen Garrett (Healy, 1986). Of course it is possible for individuals to excel in disparate areas (such as academic and athletic achievements) without this coincidence suggesting a common underlying cause. More direct evidence of an association is found in the case of Ingo Swann (Schmeidler, 1973), who is reported to have caused a change in temperature inside a sealed thermos flask at a time when he was attempting to "probe" (locate by ESP) the position of a thermometer inside the thermos. Swann produced a similar effect on a separate occasion (Puthoff & Targ, 1974), and Alex Tanous is also reported as producing detectable physical effects at the site of an ESP target on trials in which his call was correct (Osis & McCormick, 1980). These examples seem to suggest that attempts to perceive a target by ESP may involve some physical influence that could constitute a form of PK, although at present they are little more than anecdotal.

EMPIRICAL EVIDENCE THAT BEARS ON A COMPARISON OF ESP AND PK FUNCTIONING

Notwithstanding these findings from "gifted" individuals, we concur with Irwin (1985) in arguing that exploring patterns of performance across individuals engaged in PK and ESP tasks may be a more promising means of determining if these phenomena are functionally similar or different. It is disappointing, then, to note that surprisingly little empirical work directly compares performance patterns on ESP and PK tasks; indeed, there seems to have been little interest in performance patterns generally. This makes the task of making reliable judgements concerning points of similarity and difference between ESP and PK an almost impossible one if based only on already-published data. Irwin (1985), for example, has noted that although the empirical grounds for the unitarian view based on an interpretation of performance patterns is rather limited, this may be a consequence of "comparatively meagre quantities of data on performance patterns in ESP, [whereas] similar information for PK is deplorably sparse" (p. 44). Although the situation may have improved somewhat in the case of ESP since Irwin's rather damning conclusion, there has been relatively little change in the case of PK (see Roe, 1996). Where performance patterns have been considered, they may be phenomenon-specific, as Schmeidler (1994b) complained: "It has been frustrating to find that PK and ESP experiments seldom bear directly on the same question and that well-replicated results in one area often have no counterpart in the other" (p. 229). More research is needed that systematically considers the effects of the same variables on ESP and PK performance using methodologically comparable tasks.