On-line processing of tense and temporality in agrammatic aphasia.

Agrammatic aphasic individuals exhibit marked production deficits for tense morphology. This paper presents three experiments examining whether a group of English-speaking agrammatic individuals (n=10) exhibit parallel deficits in their comprehension of tense. Results from two comprehension experiments (on-line grammaticality judgment studies) suggest that these individuals are impaired for tense comprehension, and furthermore that their deficit is more pronounced for morphosemantic rather than morphosyntactic aspects of tense processing. Results from a third experiment (an elicited production study) indicate that these individuals exhibit parallel production and comprehension impairments for tense. Across the three experiments, the consistent pattern was that of a significant difficulty in associating verb forms with a pre-specified temporal context when compared to all other processes. Implications for current models of agrammatic tense and morphological deficits are discussed.