Achievement

Language impairment research faces the fundamental problems of isolating deficits to particular components of linguistic knowledge and processing, and of statistically comparing impaired and unimpaired performance on a wide variety of experimental tasks. In work with core faculty members Brenda Rapp and Colin Wilson, trainee Mike Wolmetz has applied likelihood-based methods to quantify unimpaired performance on several speech perception tasks, and demonstrated that the performance on the same tasks of patient DMN differs systematically: DMN fails to show the categorical perception effect (anomalous or 'intermediate' speech sounds are perceived as members of known linguistic categories), and DMN differs in the effect of the word/non-word status of the stimulus. DMN’s impairment results from a left temporo-parietal infarct; these results suggest that processing of speech in the right hemisphere is both more gradient and more transient than corresponding processing in the left hemisphere.