Lexical access rate of closed-class elements during auditory sentence comprehension in adults with aphasia

Abstract

Background: One hypothesis regarding the underlying impairment in agrammatic comprehension suggests that individuals with this disorder suffer from a reduction in lexical activation of closed-class words and therefore cannot appropriately construct a syntactic frame on which lexical semantic information can be applied (Friederici, 1988). Aims: Given the temporally based hypothesis, this investigation examined the effects of increased inter-word intervals (IWI) following closed-class words on auditory comprehension of various sentence types by individuals with agrammatic comprehension. It was hypothesised that providing a longer temporal window for access and processing of closedclass words would improve sentence structure comprehension. Methods & Procedures: Twelve adults with aphasia participated in an agent identification task given varying auditory sentence stimuli. Six sentence types and six IWI durations served as independent variable while accuracy and response times were measured. Outcomes & Results: Results indicated that auditory sentence comprehension performance improves when IWIs are increased. However, differences exist among individuals in response to specific IWI durations. Conclusions: Implications of delayed access rates of closed-class words in agrammatic comprehension are discussed.