Behavioral variation in Broca's aphasia has been characterized as boundless, calling into question the validity of the syndrome-based schema and related diagnostic methods of acquired language disorders. More generally, this putative variability has cast serious doubts on the feasibility of localizing linguistic operations in cortex. We present a new approach to the quantitative analysis of deficient linguistic performance, and apply it to a large data set, constructed from the published literature: Comprehension data of 69 carefully selected Broca's aphasic patients, tested on nearly 6000 stimulus sentences, were partitioned in different ways, and subjected to a series of analyses. While a certain amount of variability is indeed evident in the data, our quantitative analyses reveal a highly robust selective impairment pattern for the group: the patients' ability to analyze syntactic movement is severely compromised, in line with the Trace-Deletion Hypothesis. Further analyses suggest that patients' performance on no-movement sentence types exhibits less variation than on sentences that contain movement. We discuss the clinical and theoretical implications of our results.
Bibliographical noteFunding Information:
Supported in part by Canada Research Chairs, Canada Foundation for Innovation, and a McGill VP-Research internal grant. D. Drai’s research at the Weizmann Institute of Science is supported by the Golda and Dr. Yehiel Shwartzman and Sara and Haim Medvedi Families Postdoctoral Fellowship.
- Confidence interval
- Quantitative analysis