Event-related brain potentials during initial encoding and recognition memory of congruous and incongruous words

Event-related brain potentials (ERPs) were recorded while subjects read statements followed by words that were either semantically congruous or incongruous with the preceding phrase, and during a subsequent recognition test. Congruous words yielded smaller N400s and better memory than did incongruous statements. In addition, the ERPs to correctly recognized old words were characterized by an enhanced late positivity (P650) relative to those elicited by correctly identified new words. A second experiment essentially replicated the results of the first. In addition, the amplitude of the late positive component (P650) elicited by final words on initial exposure was predictive of subsequent recognition; words that would be later recognized were associated with a larger P650 (whether they were incongruous or not) than were words that would not be recognized. These ERP data provide evidence that within 250 ms of the presentation of a congruous word and within 450 ms of an incongruous word, a significant portion of the brain processes which determine whether a word will or will not be recognized some time in the future have taken place.