Real-time comprehension of wh- movement in aphasia: evidence from eyetracking while listening

Sentences with non-canonical wh- movement are often difficult for individuals with agrammatic Broca's aphasia to understand (, inter alia). However, the explanation of this difficulty remains controversial, and little is known about how individuals with aphasia try to understand such sentences in real time. This study uses an eyetracking while listening paradigm to examine agrammatic aphasic individuals' on-line comprehension of movement sentences. Participants' eye-movements were monitored while they listened to brief stories and looked at visual displays depicting elements mentioned in the stories. The stories were followed by comprehension probes involving wh- movement. In line with previous results for young normal listeners [Sussman, R. S., & Sedivy, J. C. (2003). The time-course of processing syntactic dependencies: evidence from eye movements. Language and Cognitive Processes, 18, 143-161], the study finds that both older unimpaired control participants (n=8) and aphasic individuals (n=12) showed visual evidence of successful automatic comprehension of wh- questions (like "Who did the boy kiss that day at school?"). Specifically, both groups fixated on a picture corresponding to the moved element ("who," the person kissed in the story) at the position of the verb. Interestingly, aphasic participants showed qualitatively different fixation patterns for trials eliciting correct and incorrect responses. Aphasic individuals looked first to the moved-element picture and then to a competitor following the verb in the incorrect trials. However, they only showed looks to the moved-element picture for the correct trials, parallel to control participants. Furthermore, aphasic individuals' fixations during movement sentences were just as fast as control participants' fixations. These results are unexpected under slowed-processing accounts of aphasic comprehension deficits, in which the source of failed comprehension should be delayed application of the same processing routines used in successful comprehension. This pattern is also unexpected if aphasic individuals are using qualitatively different strategies than normals to comprehend such sentences, as under impaired-representation accounts of agrammatism. Instead, it suggests that agrammatic aphasic individuals may process wh- questions similarly to unimpaired individuals, but that this process often fails to facilitate off-line comprehension of sentences with wh- movement.