Cognitive task demands and discourse performance after traumatic brain injury.

BACKGROUND: Social communication problems are common in adults with traumatic brain injury (TBI), particularly problems in spoken discourse. Social communication problems are thought to reflect underlying cognitive impairments.

AIMS: To measure the contribution of two cognitive processes, executive functioning (EF) and theory of mind (ToM), to the communication of adults with TBI, and to investigate the relationships between discourse performance and potential communication partners' perceptions.

METHODS & PROCEDURES: Twenty-one adults with moderate-to-severe TBI and 23 uninjured adults completed a discourse task in which EF and ToM demands were manipulated across three conditions: baseline, high-EF and high-ToM. Dependent variables were fluency (for EFs), number of mental state terms (MSTs; for ToM) and speech rate. Discourse from high-EF/ToM conditions was judged by naïve raters for social acceptability.

OUTCOMES & RESULTS: The TBI group produced significantly fewer MSTs than the comparison group across conditions and also spoke at a slower rate, and there were significant effects of condition on both measures (MST: high-EF < baseline = high-ToM; speech rate: high-EF < high-ToM < baseline). There were no significant between-groups differences in fluency or interaction of fluency with condition. MST use and fluency were associated with social acceptability ratings.

CONCLUSIONS & IMPLICATIONS: Results added further evidence of social communication problems in adults with TBI and demonstrated that discourse behaviours may negatively affect how a speaker is perceived. Results also indicated that task manipulations can affect discourse performance, suggesting that general cognitive demands may influence social communication after TBI.