The role of expectancy in hypnotic hypermnesia: a brief communication

Previous research has yielded equivocal evidence of hypnotic memory enhancement. The present experiment assessed the effects of expectancy and hypnotizability on recall for videotaped material under waking and hypnotic conditions. Ss (N = 138) were informed of hypnotic induction either before (expectancy condition) or after (no expectancy condition) watching a videotaped enactment of a crime and completing an initial waking recall test (RI). Both groups then underwent hypnotic induction, and completed the test again (R2). Ss' raw recall scores were significantly greater under hypnotic than waking conditions, but this hypermnesia was not evident when scores were corrected for mere increase in rate of responding. Ss expecting later hypnosis scored significantly higher than Ss with no such expectations, but again, this difference was not evident in corrected scores. Hypnotizability of Ss was, however, related to corrected recall, with high hypnotizable Ss displaying the greatest increase in rate of responding from R1 to R2. No evidence for the hypothesized "suppression effect" underlying hypnotic hypermnesia was found.