Lexical and Information Structure Functions of Prosody and Their Relevance for Spoken Communication: Evidence from Psychometric and Electroencephalographic Data

Prosody not only distinguishes “lexical” meaning but also plays a key role in information packaging by highlighting the most relevant constituent of the discourse, namely, “focus” information. The present study investigated the role of lexical and focus functions of prosody in the coherent interpretation of linguistic input. To this end, we manipulated the correctness of prosodic markers in the context and scrutinized how listeners evaluate these violations—whether they result in lexical or focus anomalies—using psychometric and EEG measures. Psychometric data from 40 participants indicated that prosodic violations were judged as incorrect by the listeners both at the lexical and focus levels, with focus level violations leading to lower correctness scores than lexical level violations, and combined violations receiving the lowest scores. EEG data from 20 participants documented a strong N400 effect (350–550 msec) in response to combined violations, and a late posterior negativity (600–900 msec) present only for combined violations and focus-level violations. Consistent with the psychometric data, the EEG data suggest that prosodic violations at the focus level result in higher costs for comprehension than prosodic violations at the lexical level, whereas combined prosodic violations most significantly disrupt the interpretation. Taken together, these findings suggest that the language comprehension system is sensitive to accurate representations of both lexical and information structure prosody, and benefits from the interaction between them; however, they are weighted differently based on their relevance for a functioning spoken communication.