An event-related potential study of encoding in young and older adults

Event-related brain potentials (ERPs) were recorded from young (M age=25) and older (M age=71) adults during the study phase of a recognition memory paradigm. Participants studied two temporally distinct lists of sentences (each containing two unassociated nouns). During recognition testing, in response to the nouns, participants made old/new, followed by remember (context)/know (familiarity) and temporal source (i.e., list) judgments. To assess age-related differences in encoding, the ERPs recorded during study were averaged as a function of the correctness of the judgment of old in conjunction with subsequent temporal (list correct/incorrect) and subsequent remember and know judgments, i.e., subsequent memory or Dm effects were computed. Both young and old showed robust Dm activity regardless of whether the subsequent temporal source judgment was correct or incorrect. Although both young and old produced robust Dm effects for study items subsequently associated with a remember judgment, only the older participants showed a reliable Dm effect associated with study trials that were subsequently associated with a know judgment. This pattern of results suggests that older adults did not differentially encode items that would be subsequently retrieved with context from those that would be retrieved without such attributes.