Early lexical influences on sublexical processing in speech perception: Evidence from electrophysiology

Contextual information influences how we perceive speech, but it remains unclear at which level of processing contextual information merges with acoustic information. Theories differ on whether early stages of speech processing, like sublexical processing during which articulatory features and portions of speech sounds are identified, are strictly feed-forward or are influenced by semantic and lexical context. In the current study, we investigate the time-course of lexical context effects on judgments about the individual sounds we perceive by recording electroencephalography as an online measure of speech processing while subjects engage in a lexically biasing phoneme categorization task. We find that lexical context modulates the amplitude of the N100, an ERP component linked with sublexical processes in speech perception. We demonstrate that these results can be modeled in an interactive speech perception model and are not well fit by any established feed-forward mechanisms of lexical bias. These results support interactive speech perception theories over feed-forward theories in which sublexical speech perception processes are only driven by bottom-up information.