Event-related potentials to match and mismatch letters in an immediate item recognition task

During an immediate item recognition task, ERP differences to match and mismatch letters occurred in the N1 component, as well as the P3 component, of the stimulus related wave form. The pattern of ERP differences was similar to that reported previously for words in a delayed list recognition task, (Warren, 1980). The ERP differences to match and mismatch letters appeared unaffected by visual field of presentation (left, center, right) or hemisphere of recording site (P3, P4). It is suggested that the N1-P3 differences to match and mismatch stimuli may possibly reflect a pattern of neural activity associated with a two-stage recognition memory process.