J. B. Rhine's ESP experiments

The full file

In the autumn of 1930 Joseph Banks Rhine, a botanist by training who had become an assistant professor of psychology at Duke University in Durham, North Carolina, began testing people for what he called extra-sensory perception. The work ran under William McDougall, chairman of the psychology department, with the backing of the university's president, W. P. Few. Within four years it had produced a book, Extra-Sensory Perception, which made Rhine's name, and within a decade a body of criticism that has never been settled in his favour.

What was reported

Rhine's own account, in the 1934 book, describes a slow start. Guessing games at children's summer camps and sealed-envelope tests on college classes gave results close to chance. In 1930–31 he and a colleague, Karl Zener, began testing individuals with a pack of twenty-five cards bearing five symbols, chosen chiefly by Zener: circle, rectangle, plus, star and wavy lines. A subject guessing at random should score about five in twenty-five. Rhine reported that a handful of students did much better, among them A. J. Linzmayer and a ministerial student, Hubert Pearce, and that the laboratory's trials had passed "well over 90,000". The best-known series, run by Rhine's assistant J. G. Pratt between August 1933 and March 1934, had Pratt turning cards in his office while Pearce guessed from a library cubicle across the campus. Later accounts give 558 hits in 1,850 guesses, against 370 expected by chance. The book came out under the imprint of the Boston Society for Psychic Research; the copy now digitised is the Bruce Humphries edition dated 1935.

What evidence exists, and where it is held

The record made at the time by someone other than the subjects is the laboratory's own. Its papers, donated between 1961 and 1986, are held by Duke's David M. Rubenstein Rare Book and Manuscript Library as the Parapsychology Laboratory records (RL.00992): 340 linear feet, roughly 250,000 items, of correspondence, research files, financial papers and clippings. The finding aid is candid about a gap at the start. Rhine's early assistantships are undocumented, "as are the first ESP experiments conducted at Duke (1930)", though some material survives on the work reported in the 1934 book. The second record is external: W. S. Cox's repetition at Princeton, published in the Journal of Experimental Psychology in 1936.

The book itself concedes a weakness. Walter Franklin Prince's introduction acknowledges that some series "rest, prima facie, upon the good faith of unwitnessed experimenters", arguing that the witnessed trials, Pearce's 15,000 among them, were enough without them.

What investigators concluded

Cox repeated the experiment with packs of ordinary playing cards in place of Zener cards and found "no evidence of extra-sensory perception" either in his group as a whole or in any individual. He put the difference from Rhine's figures down to "uncontrolled factors in experimental procedure or to difference in the subjects". Other psychologists published criticism through the late 1930s; the Duke finding aid names R. R. Willoughby, J. L. Kennedy, Dael Wolfle and Charles Kellogg, and says much of the dispute survives in Rhine's correspondence. The laboratory replied in 1940 with Extra-Sensory Perception after Sixty Years, written by Rhine with Pratt, Burke Smith, Charles Stuart and J. A. Greenwood, which reviewed the objections and set out tighter procedures.

The sharpest later critique came from the British psychologist C. E. M. Hansel. Reviewing his 1966 book in The New York Review of Books, Martin Gardner reported Hansel's argument that nothing in the Pearce–Pratt series ruled out Pearce leaving his cubicle and watching Pratt's cards from outside the office, which made the series "highly suspect"; Hansel did not claim that Pearce had actually done so. On a visit to Duke, Hansel showed that he could score twenty-two out of twenty-five by peeking through a gap above a door.

The leading conventional explanation

The usual explanation is laboratory procedure rather than any faculty of the mind: sensory cues between experimenter and subject, opportunities for deception that the protocols did not close, loose recording in the early unwitnessed work, and the failure of independent laboratories to find anything. Its strength is that results tended to fall away as conditions tightened and as testing moved to other hands; Cox's null result came from the first careful outside repetition. Its weakness is that it is a demonstration of possibility, not a finding of fact. No one has shown that Pearce, or anyone else at Duke, cheated, and parapsychologists replied to Hansel that his plan of the building was marked "not-to-scale", and that the window he relied on was some distance from where Pratt sat. The SPR's Psi Encyclopedia, which reports that reply, is an advocacy source, and the reply is given here in its account.

What remains disputed

Whether any of the Duke results reflected something real is still argued, though the field's own later disputes have moved to other experiments. What is settled is institutional. Duke never gave the laboratory the separate institute Rhine sought; support weakened after McDougall died in 1938 and Few in 1940, and in August 1965 the laboratory closed at Duke and became the Institute for Parapsychology of the Foundation for Research on the Nature of Man, which Rhine had set up in Durham in 1962. The records stayed with the university.

Sources

• Parapsychology Laboratory records, 1893–1984 (RL.00992) (archived) — David M. Rubenstein Rare Book & Manuscript Library, Duke University. Extent, undocumented 1930 experiments, critics named, 1940 reply, chronology to the 1965 closure.
• An experiment on extra-sensory perception (archived) — W. S. Cox, Journal of Experimental Psychology 19(4), 429–437, 1936. The independent repetition and its conclusion.
• Extra-Sensory Perception (digitised edition) — J. B. Rhine, Boston Society for Psychic Research / Bruce Humphries, 1935. Early tests, Zener's symbols, trial totals, Prince's caveat on unwitnessed series.
• Funny Coincidence (archived) — Martin Gardner, The New York Review of Books, 1966. Hansel's critique of the Pearce–Pratt series and his demonstration at Duke.
• J Gaither Pratt (archived) — Psi Encyclopedia, Society for Psychical Research. Pearce–Pratt dates, trial and hit counts; advocacy source.
• CEM Hansel (archived) — Psi Encyclopedia, Society for Psychical Research. The parapsychologists' reply to Hansel's plan of the building; advocacy source.
• Early Studies in Parapsychology at Duke (archived) — Duke University Libraries exhibit, 2021. The 1965 move to the Foundation for Research on the Nature of Man.