Abstract

Maintains that in the past criticism of J. G. Pratt and J. L. Woodruff's (1939) experiments on extrasensory perception (ESP) was based on the discovery that the significant results were concentrated in those trials made in relation to the key cards that were in the end positions in the preceding run (E-cards). Critics attributed this finding to fraud on the part of 1 of the Es on the ground that he must have kept track of those key cards from one run to the next and misplaced cards to those positions to score spurious hits. The Es, on the other hand, argued that the E-cards could have been more favorable for ESP success because of the S's psychological reaction to them. This paper describes an analysis based upon the E-card trials alone for the highest scoring S, P.M. It was found that scoring was near the chance level for those E-cards that were not shifted from the positions they occupied in the preceding run, and the results were significant only on the shifted E-cards. This finding supports the ESP interpretation of the E-card effect, and it is not consistent with C. E. Hansel's (see PA, Vol 36:2 BP99H) interpretation of E fraud. Other analyses also support the ESP hypothesis as the explanation of the results of the Pratt-Woodruff experiment.