Subject–verb agreement dependency in Turkish Broca’s aphasia: impairments in event occurrence and consequences for discourse-linking

Abstract

ABSTRACT Background: Inflecting the verb for agreement requires an intact discourse-semantic ability in addition to that for morphosyntax, since the use of person involves a link between the participants in the speech act and the morphosyntactic expression of this feature. Unlike the first person (the Speaker), the second person (the Addressee) requires additional discourse processing, termed “discourse-linking”. Individuals with Broca’s aphasia may have impaired discourse-linking, which may affect their ability to process second person pronouns and produce verb morphology for the second person. Aims: This study investigated whether the discourse-linking involved in processing second person pronouns contributes to sentence production deficits in Broca’s aphasia. Methods & Procedures: The sample consisted of 16 Turkish individuals with Broca’s aphasia (mean age: 54.8 years; SD: 14.0) who were matched in age with a control group of 16 neurologically intact Turkish individuals (mean age: 54.9; SD: 13.1). Each group completed a language task with first and second person singular or plural agreement conditions. Target agreement morphology was elicited using sentence-initial first and second person singular or plural pronouns. The plural (reference to a group) has a more complex discourse-representation than the singular (reference to an individual). Outcomes & Results: The group of individuals with Broca’s aphasia showed the following production hierarchy: first person singular (highest accuracy rate) > first person plural > second person singular > second person plural (lowest accuracy rate). There was no discrepancy between test conditions for the control group. Conclusions: The discourse-linking involved in processing second person pronouns contributes to sentence production deficits and this deficit is exacerbated by plurality in Broca’s aphasia. We suggest that cognitive-semantic intervention which focusses on the broader underlying impairment in deciphering event occurrence features (participant-time-location) could improve the use of the second person and other discourse-linked constructions (e.g., past time reference, object pronouns) which are selectively affected in Broca’s aphasia.