Event-related potentials and recognition memory: the effects of word imagery value

Event-related potentials (ERPs) were recorded from 11 subjects during a recognition memory task. Subjects were auditorily presented with 160 target words and, after about 10 min, they were engaged in a recognition task. Subjects were required to determine on each of 320 trials if the word was 'new' (never before presented) or 'old' (heard previously). In the recognition test, 160 target words and 160 non-target words were used as stimuli. To assess the effect of word imagery value, 160 stimuli (80 target and 80 non-target) were high imagery words (HI) and the remaining 160 stimuli were low imagery words (LI). Word frequency was balanced across target and non-target words. Results showed that the old/new effect was reflected by a negative component (belonging to the N400 family, Cz maximum) which was larger for new words in the 400-700 ms range. The imagery effect was also present in the 250-550 ms range of the N400, which was larger for HI stimuli. The imagery effect was present at 400-550 ms only for target words. These results confirmed the hypothesis that negative components as N400, could reflect processes occurring during the memory retrieval of items.