The objective of this research project is to characterize the ways in which the access of lexical information is disrupted in aphasia, and thereby, to provide a perspective on some of the operating properties of the lexical access system in the normal brain. The research encompasses two aspects of this processing stage: 1) phonological factors in lexical access; and 2) the time course of semantic activation during lexical access. The phonologically based studies examine the possibility that Broca's aphasic patients have a heightened threshold for addressing lexical entries, whereas Wernicke's aphasic patients have a decreased sensitivity to phonetic feature contrasts. The studies of the time course of activating word meanings explores the possibility that in Broca's aphasia, but not Wernicke's aphasia, the activation of a word's semantic domain proceeds in an abnormally slow fashion, thus disrupting further - particularly syntactic - processing. Both sets of experimental inquiries make use of reaction time methodologies and the lexical decision paradigm to allow assessment of the lexical access processes as they unfold in real-time. This program of study should yield a fuller picture of information-access disruptions in aphasia and provide a basis for implementing appropriate forms of language remediation.
