Working memory capacity dissociates lexical and sentential context effects

Semantically associated and unassociated word pairs were embedded in normal meaningful sentences and in sentences that were semantically anomalous throughout. The influence of lexical context was isolated via comparison of responses to the second words of the associated and unassociated pairs. The influence of sentence-level context was isolated by comparing responses to the same words in the two sentence types. Subjects of high, medium, and low working memory capacity (as evaluated by the reading span test) showed modulations of event-related brain potentials in response to lexical context. In contrast, only the high- and medium-capacity groups were responsive to purely sentence-level semantic context. The results demonstrate that sentential context influences the processing of words in intermediate sentence positions at normal reading speeds, but that the on-line utilization of this context is more demanding of working memory than single-word contexts.