Slower-than-normal syntactic processing in agrammatic Broca's aphasia:: Evidence from Dutch

Studies of agrammatic Broca's aphasia reveal a diverging pattern of performance in the comprehension of reflexive elements: offline, performance seems unimpaired, whereas online - and in contrast to both matching controls and Wernicke's patients-no antecedent reactivation is observed at the reflexive. Here we propose that this difference characterizes the agrammatic comprehension deficit as a result of slower-than-normal syntactic structure formation. To test this characterization, the comprehension of three Dutch agrammatic patients and matching control participants was investigated utilizing the cross-modal lexical decision (CMLD) interference task. Two types of reflexive-antecedent dependencies were tested, which have already been shown to exert distinct processing demands on the comprehension system as a function of the level at which the dependency was formed. Our hypothesis predicts that if the agrammatic system has a processing limitation such that syntactic structure is built in a protracted manner, this limitation will be reflected in delayed interpretation. Confirming previous findings, the Dutch patients show an effect of distinct processing demands for the two types of reflexive-antecedent dependencies but with a temporal delay. We argue that this delayed syntactic structure formation is the result of limited processing capacity that specifically affects the syntactic system. (c) 2006 Elsevier Ltd. All rights reserved.