Sentence context affects the brain response to masked words

Historically, language researchers have assumed that lexical, or word-level processing is fast and automatic, while slower, more controlled post-lexical processes are sensitive to contextual information from higher levels of linguistic analysis. Here we demonstrate the impact of sentence context on the processing of words not available for conscious report by recording ERPs as sentences ended congruously or incongruously. Sentence final words were either masked to prevent their conscious identification, or were unmasked. For both masked and unmasked words, congruous completions elicited less negative ERPs than incongruous ones between 300 and 500 ms after word onset (N400). Relative to the unmasked words, congruity effects in masked words were much smaller, began slightly later, and displayed a more anterior distribution. Results suggest contextual priming effects indexed by the N400 component reflect both automatic and controlled processes. Data are interpreted as suggesting a link between the neural generators of the N400 and conceptual short-term memory, a dynamic process for conceptual activation and structuring that is triggered by perceptual input.