This study addresses the question whether prosodic information can affect the choice for a syntactic analysis in auditory sentence processing. We manipulated the prosody (in the form of a prosodic break; PB) of locally ambiguous Dutch sentences to favor one of two interpretations. The experimental items contained two different types of so-called control verbs (subject and object control) in the matrix clause and were syntactically disambiguated by a transitive or by an intransitive verb. In Experiment 1, we established the default off-line preference of the items for a transitive or an intransitive disambiguating verb with a visual and an auditory fragment completion test. The results suggested that subject- and object-control verbs differently affect the syntactic structure that listeners expect. In Experiment 2, we investigated these two types of verbs separately in an on-line ERP study. Consistent with the literature, the PB elicited a closure positive shift. Furthermore, in subject-control items, an N400 effect for intransitive relative to transitive disambiguating verbs was found, both for sentences with and for sentences without a PB. This result suggests that the default preference for subject-control verbs goes in the same direction as the effect of the PB. In object-control items, an N400 effect for intransitive relative to transitive disambiguating verbs was found for sentences with a PB but no effect in the absence of a PB. This indicates that a PB can affect the syntactic analysis that listeners pursue.

Speech is structured into parts by syntactic and prosodic breaks. In locally syntactic ambiguous sentences, the detection of a syntactic break necessarily follows detection of a corresponding prosodic break, making an investigation of the immediate interplay of syntactic and prosodic information impossible when studying sentences in isolation. This problem can be solved, however, by embedding sentences in a discourse context that induces the expectation of either the presence or the absence of a syntactic break right at a prosodic break. Event-related potentials (ERPs) were compared to acoustically identical sentences in these different contexts. We found in two experiments that the closure positive shift, an ERP component known to be elicited by prosodic breaks, was reduced in size when a prosodic break was aligned with a syntactic break. These results establish that the brain matches prosodic information against syntactic information immediately.