Residual effect of suggestions for posthypnotic amnesia: a reexamination.

Despite the significant recovery of memory observed after suggestions for posthypnotic amnesia are canceled, there still remains an apparent deficit in total recall (after amnesia has been lifted) among subjects who show amnesia on initial testing. This effect, reported originally by Hilgard and Hommel in 1961, was confirmed in analyses of recall data from groups of 691 and 488 volunteer subjects who were administered a standardized, tape-recorded hypnotic procedure. Hypnotizable subjects who initially showed posthypnotic amnesia recalled significantly fewer items after amnesia was removed than did hypnotizable subjects who were initially nonamnesic. Further analysis showed that the residual amnesia effect was not an artifact of the very low level of posthypnotic recall performance shown by pseudoamnesic subjects, failure of memory storage due to such factors as inattention or sleep, or the differential time constraints on the memory reports of previously amnesic and nonamnesic subjects. Residual posthypnotic amnesia may reflect the fact that suggested posthypnotic amnesia, when lifted, takes time to fully dissipate.