Factor analysis of aphasic syntactic comprehension disorders

Background: Many people with aphasia have impaired sentence comprehension. Previous studies using factor analysis have suggested that a single factor accounts for performance on measures of sentence comprehension (e.g., Caplan, Baker, & Dehaut, 1985). However, this work has been limited to measures of accuracy on single sentence comprehension tasks. Aims: The purpose of this study is to further examine the factor structure underlying aphasic sentence comprehension using accuracy, reaction time (RT), and on-line measures using both exploratory and confirmatory factor analyses. Methods & procedures: A total of 42 people with aphasia and 40 non-brain-damaged controls were tested on 11 sentence types and five tasks. Accuracy and RT data are reported for the whole sentence presentation version of sentence-picture matching, and accuracy data are reported for object manipulation. Confirmatory factor analyses examining measurement invariance across groups and tasks are presented. Exploratory factor analyses of on-line syntactic processing are also presented. Outcomes & results: Results indicated that one-factor models best account for accuracy and RT data. Measurement of factors was partially invariant across groups and tasks. Factor structures suggestive of syntactic processes emerged in the analyses of on-line measures. Conclusions: This study suggests that syntactic processes may load on separate factors during on-line parsing and that syntactic processes do not dissociate when the parser's output is used in the service of a task at the end of the sentence.