Cognitive slowing in closed-head injury.

Mean response times (RTs) from a sample of 13 simple- and choice-reaction time studies (which included 353 Closed-Head Injury (CHI) subjects at various stages of injury and 329 Control, non-CHI, subjects; mean age of both groups, approximately 28 years) were analyzed using Brinley Plot/multiple regression analysis techniques to provide support for the observation that CHI results in a slowing of basic cognitive information processing. Across 101 experimental conditions, the best-fit equation that resulted from regressing the CHI data onto the Control data for matched conditions was Y(CHI)=1.54X(control)-59, and this specific regression equation accounted for approximately 89% of the variance (based on R2). These results suggest that the basic cognition processes involved in simple- and choice-reaction time performance were approximately 1.54 times slower in CHI individuals in this sample as compared to non-CHI individuals. This pattern of performance substantiates the observation the CHI results in a slowing of even very basic cognition information processes.