Event-related potentials show online influence of lexical biases on prosodic processing.

This event-related potential study examined how the human brain integrates (i) structural preferences, (ii) lexical biases, and (iii) prosodic information when listeners encounter ambiguous 'garden path' sentences. Data showed that in the absence of overt prosodic boundaries, verb-intrinsic transitivity biases influence parsing preferences (late closure) online, resulting in a larger P600 garden path effect for transitive than intransitive verbs. Surprisingly, this lexical effect was mediated by prosodic processing, a closure positive shift brain response was elicited in total absence of acoustic boundary markers for transitively biased sentences only. Our results suggest early interactive integration of hierarchically organized processes rather than purely independent effects of lexical and prosodic information. As a primacy of prosody would predict, overt speech boundaries overrode both structural preferences and transitivity biases.