ERPs to prosodic processing in normal and deviant speech

Pannekamp, A., Toepel, U., Alter, K., Hahne, A., and Friederici, A. D.
Max Planck Institute of Cognitive Neuroscience, Leipzig, Germany

The paper at hand describes four experiments systematically investigating the brain's response to the perception of sentences containing differing quantities of linguistic information. Spoken language generally provides various levels of information for the interpretation of the incoming speech stream, namely phonemic, syntactic, semantic, and prosodic information. In this paper, we focus on the processing of prosodic phrasing, but especially on its interplay with the other basic sources of linguistic information mentioned above. An EEG paradigm was chosen to record the online responses to processing on single sentence level. For the perception of major prosodic boundaries the Closure Positive Shift (CPS) has been manifested as a reliable and easy to replicate event-related component. It has mainly been shown to correlate to Intonational phrase boundaries (IPh; Selkirk, 1984) in speech. However, to define this component as exclusively relying on the prosodic information in the speech stream it is necessary to systematically vary the linguistic content of the stimulus material. This was done by creating quasi-natural sentence material with decreasing semantic and syntactic information, i.e. jabberwocky sentences (where all content words were replaced by meaningless words), pseudo word sentences (replacement of all function and content words with meaningless words), and delexicalized sentences (hummed intonation contour of a sentence removing all segmental content). In all sentence types a Closure Positive Shift in correlation to the perception of Intonational phrase boundaries has been identified.