Karsten Steinhauer
Georgetown University
The P600 component in event-related potentials (ERPs) is elicited by syntactic anomalies (i.e., violations, garden-path sentences, complex structures) and has also been referred to as syntactic positive shift (SPS). Here, I summarize previous P600/SPS findings and present data from six ERP experiments that argue against a purely syntactic P600 account, considering in particular the contribution of phonological factors.
In previous studies, inconsistent data on the behavior of the P600 (e.g., concerning probability manipulations; "P600/P300 debate") and variability of the P600's topographical distribution indicated the involvement of different neural generators. Moreover, P600-like components have also been reported (1) for musical rather than linguistic structure violations; and (2) for salient word markings (e.g., words written in CAPITAL letters) that are likely to trigger subvocal accentuation, compatible with a phonological impact.
Previous behavioral research (without ERPs) suggests that the strength of syntactic garden-path effects depends on the involvement of prosody [1]. Based on these findings, the present ERP study (six experiments, N=109 subjects) examined the P600 of a reverse syntactic garden-path effect in spoken and written German, induced by either prosodic boundaries [2] or commas [3] (see example below). As expected, the P600 amplitude increased with the degree to which phonological representations were involved. Thus the data strongly suggest that the P600 is not a monolithic ERP component and that phonological factors may play an important role during the processes reflected by this 'syntactic' positive shift.
Example in German
Peter verspricht # Anna zu arbeiten und das Büro zu putzen.
Similar example in English
Since Jay always jogs # a mile and a half this seems like a short distance to him.
(Note: # = prosodic boundary or comma. The disambiguating target words are underlined)
References
[1] Bader, M. (1998). Prosodic influences on reading syntactically ambiguous sentences. In J. D. Fodor & F. Ferreira (Eds.), Reanalysis in Sentence Processing, 1-46. Kluwer, Dordrecht.
[2] Steinhauer, K., Alter, K., & Friederici, A. D. (1999). Brain potentials indicate immediate use of prosodic cues in natural speech processing. Nature Neuroscience, 2:191-96.
[3] Steinhauer K & Friederici AD (2001). Prosodic boundaries, comma rules, and brain responses: The closure positive shift in ERPs as a universal marker for prosodic phrasing in listeners and readers. Journal of Psycholinguistic Research, 30:267-95.