title: Event-related brain potentials dissociate repetition effects of high- and low-frequency words.
abstract: Event-related brain potentials (ERPs) were recorded while subjects detected nonwords interspersed among sequences of words of high or low frequency of occurrence. In Phase 1, a proportion of the words were repeated after six intervening items. In Phase 2, which followed after a break of approximately 15 min, the words were either repeats of items presented in the previous phase or new. Unrepeated low-frequency words evoked larger N400 components than did high-frequency items. In Phase 1, this effect interacted with repetition, such that no frequency effects were observed on N400s evoked by repeated words. In addition, the post-500-msec latency region of the ERPs exhibited a substantial repetition effect for low-frequency words, but did not differentiate unrepeated and repeated high-frequency words. In Phase 2, ERPs evoked by "old" and "new" high-frequency words did not differ in any latency region, while those evoked by old and new low-frequency words differed only after 500 msec. The interactive effects of frequency and repetition suggest that these variables act jointly at multiple loci during the processing of a word. The specificity of the post-500-msec repetition effect for low-frequency words may reflect a process responsive to a discrepancy between words' intra and extraexperimental familiarity.
authors.affiliation: Wellcome Brain Research Group, Department of Psychology, University of St. Andrews, Fife, United Kingdom.
authors.forename: M D
authors.initials: MD
authors.lastname: Rugg
mesh_terms: D000328:Adult; D001143:Arousal; D001288:Attention; D004569:Electroencephalography / Q000295:instrumentation; D005074:Evoked Potentials, Visual; D006801:Humans; D008568:Memory; D011939:Mental Recall; D011930:Reaction Time; D011932:Reading; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D014706:Verbal Learning