Evaluating hypnotic memory enhancement (hypermnesia and reminiscence) using multitrial forced recall.

Two experiments investigated whether hypnosis enhances memory retrieval per se or merely increases a person's willingness to report recollections. Both experiments assessed immediate and delayed (i.e., 1 week) recall for pictorial stimuli. In Experiment 1, following an initial waking baseline recall, subjects of high or low hypnotic ability completed a series of recall trials conducted either in hypnosis or in the walking condition. The classic hypermnesia effect was obtained, but with no supplemental contribution of hypnosis. In Experiment 2, hypnosis was introduced only after 6 waking-recall trials. Hypnosis again failed to enhance retrieval of new correct items, although it increased the production of new incorrect recall among hypnotizable individuals. The findings provide no evidence for alleged hypermnesic properties of hypnosis.