Guillem et al. (2001) studied ERP old/new effects in 15 schizophrenia patients and 15 healthy controls during a continuous recognition memory paradigm with unfamiliar faces under implicit (indicate the gender) and explicit (item previously presented) task instructions. Using a 13-channel EEG montage referenced to the right ear lobe, reduced old/new effects were reported in patients over medial parietal sites for the implicit task at about 300 ms, overlapping a relative negative ERP deflection (N300), but not at about 500 ms, overlapping a late positive complex (P500). During the explicit task, patients performed substantially poorer than controls (but nevertheless clearly above chance) and showed reduced old/new effects over posterior sites during a prolonged late positive complex at about 500 ms (N500), but not at 700 ms (P700). In the same task, however, patients had an enhanced late old/new effect over frontal sites, rendering a complex and difficult to interpret pattern of old/new effects.
