This study examined the effect of linguistic context on the graded structure representation of common categories in adults with traumatic brain injury (TBI). Graded structure indicates that all members of a category are not equally representative with some members being better examples than others. Ten adults who had suffered traumatic brain injuries as the result of motor vehicle accidents and 10 age- and gender-matched neurologically intact adults participated in the study. The experimental task consisted of presenting each participant with 20 contextual sentences and asking them to select the best example of a category label mentioned in each sentence. Each of the 20 sentences were followed by six exemplars: four exemplars of the common category label mentioned in the sentence and two exemplars that were members of other categories. The specific exemplar of the category label was inferred by the context meaning. The neurologically intact adults were significantly more accurate than the TBI adults in choosing the best category example. However, error patterns were similar for each group with both groups choosing a significantly higher proportion of true unrelated exemplars than any other type of error. Results are discussed relative to the process of restructuring common category graded structure as a result of semantic constraints imposed by linguistic context and limitations in cognitive flexibility observed in TBI adults.
