Left-edge boundary tone and main clause verb effects on syntactic processing in embedded clauses – An ERP study

We examined the effects of main clause verb pragmatics and left-edge boundary tones on syntactic processing in Swedish embedded clauses, using listener judgments and Event-Related Potentials. When the syntactic structure did not match the expectation based on the occurrence of a left-edge boundary tone, the acceptance rate decreased significantly, and a biphasic positive effect with an early peak (P345) and a late peak (P600) showed increased processing load. A larger continuous positive effect (P600) was obtained by changing an assertive main clause verb to a nonassertive verb, thereby modifying the lexical pragmatic context of the embedded clause. Increased positivity was also seen at the left-edge boundary tone when it mismatched a preceding nonassertive verb. We conclude that left-edge boundary tones are used in addition to verb pragmatics to guide the syntactic processing of embedded clauses in Swedish, and that pragmatic and prosodic information is integrated immediately.