My major research interests are in the psychology and neuropsychology of language. One interest, which I have been pursuing for many years, is the nature of verbal short-term memory and its role in language comprehension and production and in long-term learning. The basic premise being investigated is that there are separable phonological and semantic contributions to short-term memory which play differing roles in sentence comprehension and production. With regard to long-term learning, it is hypothesized that the short-term retention of phonological information is necessary for the development of a long-term memory representation for new phonological forms (i.e., new words) whereas the short-term retention of semantic information is necessary for the long-term learning of new lexical-semantic representations. A new direction in this research is relating basic cognitive processes of inhibition, set-shifting and updating to short-term memory patterns. We hypothesize that patients who show a deficit in retaining semantic information in short-term memory have difficulty inhibiting irrelevant semantic information. Another interest is the nature of the codes and processes involved in reading and spelling. We have been looking at the units of spelling-sound correspondence in reading through the analysis of the pattern of disrupted reading in surface and phonological dyslexic patients. We have found evidence of multiple units from grapheme to onset-body to syllable to morpheme. We have recently been addressing the issue of whether the same orthographic representations are used in reading and spelling. These issues are being addressed by studying brain-damaged patients with language deficits and by more traditional experimental studies with normal subjects. Recent approaches include the development of event-related potential and neuroimaging studies of working memory and sentence comprehension. One long-standing area of interest in our lab is the relation between short-term memory (STM) and language processing. Most aphasic patients (i.e., patients who have a language deficit after brain damage) have both reduced STM spans and impaired comprehension and production. In research sponsored by NIH we are investigating the different types of STM deficits displayed by aphasic patients and the relation of these deficits to language processing. We are also investigating this relation in normal subjects by examining the effects of memory load on comprehension and production. A recent interest is the relation of short-term memory deficits to deficits in long-term learning. We are examining this relation for both explicit and implicit memory tests. Another interest is the nature of the codes and processes involved in reading and spelling. We have been looking at the units of spelling-sound correspondence in reading through the analysis of the pattern of disrupted reading in surface and phonological dyslexic patients. We have found evidence of multiple units from grapheme to onset-body to syllable to morpheme. We have recently been addressing the issue of whether the same orthographic representations are use din reading and spelling. These issues are being addressed by studying brain-damaged patients with language deficits and by more traditional experimental studies with normal subjects. Recent approaches include neuroimaging studies of working memory and sentence comprehension and production.
Publications/Creative Works
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