Pronominal resolution and gap filling in agrammatic aphasia: evidence from eye movements

Abstract

This paper reports the results of three studies examining comprehension and real-time processing of pronominal (Experiment 1) and Wh-movement (Experiments 2 and 3) structures in agrammatic and unimpaired speakers using eyetracking. We asked the following questions: (a) Is off-line comprehension of these constructions impaired in agrammatic listeners?, (b) Do agrammatic, like unimpaired, listeners show eye movement patterns indicative of automatic pronominal reference resolution and/or gap-filling?, and (c) Do eyetracking patterns differ when sentences are correctly versus incorrectly interpreted, or do automatic processes prevail in spite of comprehension failure? Results showed that off-line comprehension of both pronoun and Wh-movement structures was impaired in our agrammatic cohort. However, the aphasic participants showed visual evidence of real-time reference resolution as they processed binding structures, including both pronouns and reflexives, as did our unimpaired control participants. Similarly, both the patients and the control participants showed patterns consistent with successful gap filling during processing of Wh-movement structures. For neither pronominal nor movement structures did we find evidence of delayed processing. Notably, these patterns were found for the aphasic participants even when they incorrectly interpreted target sentences, with the exception of object relative constructions. For incorrectly interpreted sentences, we found end of sentence lexical competition effects. These findings indicate that aberrant lexical integration, rather than representational deficits or generally slowed processing, may underlie agrammatic aphasic listener's comprehension failure.

Fig. 1

Sample visual picture panel using in Experiment 1. In the reflexive condition, e.g., The soldier told the farmer with glasses to shave himself in the bathroom., the farmer is the target and soldier is the competitor. For the pronoun condition, e.g., The soldier told the farmer with glasses to shave him in the bathroom., the soldier is the target and the farmer is the competitor

Fig. 2

Proportion of fixations to target, competitor, and object items displayed in the visual panels across sentence regions in the reflexive condition for control participants (a) and aphasic participants (b). Error bars represent standard errors

Fig. 3

Proportion of fixations to target, competitor, and object items displayed in the visual panels across sentence regions in the pronoun condition for control participants (a) and aphasic participants (b). Error bars represent standard errors

Fig. 4

Proportion of fixations to target and competitor items across sentence regions for correct and incorrect trials for the aphasic participants

Fig. 5

Sample visual array used in Experiment 2. For structures such as “Who did the boy kiss that day at school”? and “Did the boy kiss the girl that day at school”?, the boy is the agent and the girl is the theme

Fig. 6

Theme preference for yes–no questions, for both the unimpaired and aphasic listeners, across sentence regions. The theme preference computed the difference for theme minus agent fixations. For the question, “Did the boy kiss the girl that day at school”?, fixations to the girl minus fixations to the boy were computed. Region 1 = Subject; Region 2 = Verb; Region 3 = Object/Gap; Region 4 = Location, and Post-offset. Error bars reflect standard errors

Fig. 7

Theme preference for object extracted wh-question structures, for both the unimpaired and aphasic listeners, by sentence region. The theme preference computed the difference score for theme minus agent fixations. For the question, “Who did the boy kiss that day at school”?, fixations to the girl minus fixations to the boy were computed. Region 1 = Subject; Region 2 = Verb; Region 3 = Object/Gap; Region 4 = Location, and Post-offset. Error bars reflect standard errors

Fig. 8

Theme preference found for aphasic participants' correctly and incorrectly comprehended sentences by sentence region. The theme preference computed the difference score for theme minus agent fixations. Note the theme preference for incorrect responses in Regions 2 and 3, which shifted to a negative theme preference in Regions 4 and 5, coinciding with their incorrect interpretation of the sentence. Region 1 = Subject; Region 2 = Verb; Region 3 = Object/Gap; Region 4 = Location, and Post-offset. Error bars reflect standard errors

Fig. 9

Sample visual array used in Experiment 3. For the critical sentence: Point to who the bride was ticking in the mall., agent (competitor) = bride; Theme (target) = groom; Location = Mall; distractor = clerk

Fig. 10

Eye movement patterns occurring across sentence regions during object relative sentence processing. a Eye fixation (theme preference) data for aphasic and unimpaired control participants. b Eye fixations (theme preference) during correct and incorrect trials for the aphasic participant group