Discourse coherence and cognition after stroke: a dual task study

Several researchers have suggested that the maintenance of global coherence (topic maintenance) and local coherence (maintenance between utterances) in discourse requires cognitive resources. This study directly tests this hypothesis by examining the relationship between cognitive variables and coherence in narrative discourse produced by mobility-impaired stroke survivors under single (talking) and dual (talking and walking) task conditions. Although there were no effects of the dual task on coherence, global coherence was significantly disrupted regardless of the single or dual task condition. Moreover, global coherence strongly correlated with cognitive function measures, whereas local coherence did not. Findings are consistent with two interpretations: (1) that global and local coherence may be subserved by different cognitive processes or (2) that maintaining global coherence is a more difficult task and thus will show effects of cognitive impairment before local coherence is impaired. These are both testable hypotheses for future research.

After reading the manuscript, the reader will be able to: (1) understand and differentiate between local and global measures of coherence; (2) discuss the effects of a dual task, walking and talking, on global coherence in a gait-impaired group of stroke survivors; (3) understand why the maintenance of global coherence in discourse might be more cognitively demanding than the maintenance of local coherence.