Measurement of Implicit Memory Using PDP (1)

Explicit memory referes to intentional or conscious recollection of prior experiences; implicit memory, by contrast, referes to changes in performance or behavior that are produced by prior experiences on tests that do not require any intentional or conscious recollection of those experiences. The dissociation have been produced both by a variety of experimental manipulations in normal subjects and by demonstrations that amnesic patients show intact implicit memory despite impaired explicit memory. Perhaps the most intensively studied type of implicit memory is known as repetition or direct priming. The process dissociation procedure (PDP) proposed by Jacoby (1991) provide an escape from problems of identifying processes with tasks. The goal of the PDP is to estimate separately the influences of different bases for recognition memory decisions. The purpose of this experiment was to examine the validity of PDP using words as stimuli instead of pictures that were adopted in Fukuda's experiment (1995) and to computerize it to measure subject's response time. The second purpose was to examine the effect of frequency of word appearance on implicit memory. Subjects were 40 undergraduate students and were assingned to 4 groups. The experiment was run in two phases, where the first phase was study phase, and the second phase was the recognition test. The first list of words (List A) was presented visually on the display with blue for background color-frame, and the second list of words (List B) was also presented visually on it with red for background color-frame. The recognition test list (List A+B+C) was also presented visually on the display and subjects were requested to press either "yes-key (old words)" or "no-key" (new words) under either inclusion or exclusion test instruction. The estimated probabilities of calling old words on the basis of recollection and familiarity were caluculated according to previous report (Jacoby, 1991). There was not significant differences between recollection and familiarity in frequency of word appearance. Also, it was concluded that the procedure used in this experiment was valid on the basis of the estimated probability and previously reported probability. It is necessary to replicate these type of experiments and compare with different type of experiments in order to standerdize the method measuring implicit memory and explicit memory