Hypermnesia for Socratic stimuli: The growth of recall for an internally generated memory list abstracted from a series of riddles.

Hypermnesia (the increase of recall with time and effort) was tested and contrasted for three conditions of input, each thought to involve different levels of cognitive processing. The basic design involved a multitrial free recall procedure, with groups differing only in the presentation of materials to be remembered. The words subjects (most superficial cognitive processing) recalled a serial list of 40 words; the pictures subjects recalled the same series of 40 pictures; and the Socratic subjects (deepest cognitive processing) recalled an internally generated memory set consisting of covert solutions to 40 riddles, which had been pretested to yield the same 40 items as those of the other groups. While all groups showed spontaneous recovery of additional items on repeated recall without further presentation, as well as faster retrieval rates in early portions of successive recall trials, the increase in the number of items recalled on each trial was greatest for the Socratic group, intermediate for the pictures group, and least for the words group, suggesting that the greater the depth of cognitive processing, the greater the magnitude of hypermnesia.