In the company of other words: Electrophysiological evidence for single-word and sentence context effects

The qualitative and quantitative similarities between lexical and sentence-level context effects were assessed by means of scalp-recorded electrophysiological measures. Event-related brain potentials (ERPs) were recorded to the second of a pair of words in a delayed letter search task and to the final words of a series of sentences presented one word at a time, and read for meaning and subsequent recognition. The critical words in both context conditions varied in the degree to which they were semantically or associatively related to the preceding context. In both cases, the ERPs to the critical words were associated with N400 components whose amplitude varied with expectancy and association. Neither the latency nor scalp distribution of the early phase of these two N400 effects differed as a function of context; the effects differed only in amplitude, with the word-level effect being smaller. Thus, as indexed by the N400 effect, there appears to be a remarkable qualitative similarity between the processes subserving lexical and sentence-level context effects.