Syntax and semantics?

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Understanding sentences involves both semantic and syntactic processing. It is a matter of debate to what extent syntax is different from, or dependent on, semantics. One way to investigate this issue is by using event-related potentials (ERPs). Experiments have shown that semantic–pragmatic anomalies in sentences (such as the unexpected word ‘bake’ in ‘the cats won’t bake the food’) yield an N400 component in the ERP of the subject (a negative potential occurring around 400 ms after onset of the critical word), relative to an expected sentence (‘the cats won’t eat the food’). Syntactic violations, on the other hand (such as ‘the cats won’t eating…’), elicit a different waveform: a P600 (a positive potential with an onset of about 600 ms) (see Ref. 1xEvent-related brain potentials and human language. Osterhout, L., McLaughlin, J., and Bersick, M. Trends Cognit. Sci. 1997; 1: 202–209Abstract | Full Text PDF | Scopus (68)See all ReferencesRef. 1 for a review). These different ERP responses suggest that semantic processing has a different neural substrate from syntactic processing. An interesting further question is to see what happens in double anomalies (such as ‘the cats won’t baking…’. If the ERP profile for a double anomaly is the linear sum of the ERP components for a semantic anomaly and a syntactic violation, then it is likely that the N400 and P600 are generated by independent neural sources. This in turn would suggest that these components reflect independent cognitive processes. Previous studies using double anomalies have yielded conflicting results, but in a recent study by Osterhout and Nicol, the authors report an (approximately) linear summation of the N400 and P600 in the doubly anomalous condition in their experiment2xOn the distinctiveness, independence and time course of the brain responses to syntactic and semantic anomalies. Osterhout, L. and Nicol, J. Lang. Cognit. Process. 1999; 14: 283–317Crossref | Scopus (149)See all References. This carefully controlled study provides more substantial support for the claim that semantic processing is distinct and independent from syntactic processing, at least with respect to the processing of the specific semantic and syntactic anomalies investigated by the authors. Just how far-reaching their conclusions are will have to wait for the results of further experiments in this area.