The neuropsychology of sentence processing: Where do we stand?

Abstract

In the early 1980s, sentence comprehension deficits were attributed to a loss of syntactic knowledge in agrammatic Broca's aphasics and to a short-term memory deficit in conduction aphasics. Findings in the remainder of the decade called both of these claims into question and presented general difficulties for the group study approach. Results from case studies support the representational independence of syntactic and semantic information but the interaction of these knowledge sources during processing. Working memory is still considered to provide critical constraints on sentence comprehension, but the capacity involved appears to be largely independent of the phonological storage involved in word list recall. Current computational approaches to sentence comprehension provide the means of accounting for the interaction of multiple sources of information and working memory requirements, but have yet to be tested against neuropsychological findings.

Acknowledgments

The writing of this manuscript was supported by NIH grant DC-00218 to Rice University. The author would like to thank Meredith Knight for her help with technical aspects of this manuscript.

Notes

 Gahl (2002) found no significant effect for verb bias for the Broca's aphasics, although the effect was significant for the fluent aphasics. However, there were only 5 Broca's aphasics, but 12 fluent aphasics, and thus the lack of significance for the Broca's aphasics is most likely due to a lack of power. In fact, the size of the difference between sentences that matched or did not match verb bias was at least as large for the Broca's aphasics. No direct statistical comparison was made between the results for the Broca's aphasics and the fluent aphasics.

 Patient MP reported by Martin et al. (1995) showed reduced span and an absence of phonological effects for visually presented word lists, whereas his span for auditory lists was normal. His comprehension of visually presented relative clause sentences, even when presented rapidly in a word-by-word fashion, was normal.