Ecological validity in assessment of discourse in traumatic brain injury: ratings by clinicians and non clinicians

Researchers studying discourse after traumatic brain injury TBI increasingly recognize the need to take account of variation within the non brain damaged NBD population in order to validate their findings. This study investigated the use of ratings by professional clinicians trained in speech pathology P raters and by peers of TBI individuals NP raters as a method of placing TBI individuals com munication in context. Twenty TBI adults and 20 NBD controls matched for age, sex, education and social background retold a 1400 word story presented on audiotape, following which the narratives were transcribed and segmented. Raters used two 5 point scales, representing independent parameters of Content and Clarity, to rate the transcripts. Statistical analysis demonstrated that P raters tended to give higher ratings across the board than NP raters but that P and NP ratings were also highly correlated. In general, the ratings assigned to the two subject groups overlapped and exhibited an even spread across the range of mean ratings. On the evidence of this study clinicians appear to share perceptions regarding discourse performance with peers of the TBI subjects. In addition, many TBI subjects perform as well or better than NBD controls on high level tasks.