Inference in right hemisphere damaged individuals' comprehension: the role of sustained attention.

The ability to make inferences for the purposes of comprehension is considered an important factor in pragmatic ability. In this experimental group study with stroke patients, the ability to make inferences and its associations with sustained attention and verbal working memory were explored. A group of 14 left-hemisphere-damaged individuals had more difficulty with tasks requiring the ability to revise inferences than a matched control group. Their results on those tasks tended to be associated with verbal working memory capacity. A group of 14 right-hemisphere-damaged (RHD) individuals also had problems in revising inferences, but their results were associated with sustained attention. In addition, the RHD subjects had problems in making inferences about characters' attitudes or motives. A lack of significant differences in results on tasks between the groups of brain damaged individuals indicate that comprehension of complex information might be impaired post stroke, irrespectively of whether the damage is to the left or right hemisphere. The results suggest that sustained attention, whilst not being a solitary sufficient factor, might somehow be involved in comprehension problems related to RHD. Implications for further research and clinical management of these sometimes subtle problems are discussed.