Case Marker Assignment Abilities as a Function of the Noun Types of Thematic Roles in Aphasia

Abstract

Objectives: The purpose of this study was to investigate the ability in case marker (CM) assignment according to noun types of thematic roles in people with aphasia (PWA). CM errors were analyzed and the correlation between noun types and the severity of aphasia was examined. Methods: Eighteen PWA and twenty normal adults participated in this study. The CM assignment task was conducted by presenting participants with two different noun types of thematic roles and one verb, and the participants were asked to produce the appropriate CM for each noun. Responses were calculated by accuracy (%) and the error types were analyzed. Results: First, PWA performed significantly lower than the normal adults, especially in instrument nouns of thematic roles when compared with location and theme. Second, PWA showed four times more substitution errors than omission errors, which is a representative characteristic in inflectional languages. Instrumental and locative CMs were mostly substituted with accusative CMs, and accusative CMs were mostly substituted with locative CMs. The most predictable variable for aphasia severity were the location nouns of thematic role, at approximately 48.2%. Conclusion: PWA showed significantly lower accuracy compared to normal adults, indicating that PWA have difficulties in comprehending syntactic and semantic relationships between arguments. Since lexical retrieval is highly related to the frequency effect and PWA have highly preserved spatial cognition, syntactic processing abilities were mostly affected in comprehending location thematic roles. Thus, the location was highly correlated to aphasia severity. Moreover, CM assignment may be clinically useful because it is simple to conduct and can be used for deep testing. © 2020 UKSS and NASS