THE EFFECT OF CHARACTER AND ARRAY TYPE ON VISUAL-SPATIAL SEARCH QUALITY FOLLOWING TRAUMATIC BRAIN INJURY

Disorder; of visuomotor function are common following traumatic brain injury (TBI), but spatially directed visual attention has received lit tle study in this population. 'Cancellation' testing is a common, beds ide method for assessing directed attention, which can provide informa tion on how task properties influence visual scanning and search follo wing severe TBI. Groups of 20 individuals after severe TBI and 21 heal thy control subjects were matched for age and education. Participants performed finger tapping tests to assess motor speed as well as four c ancellation tests employing letter and geometric figure stimuli in ran dom and structured arrays. Control and TBI groups differed significant ly on measures of accuracy, task completion time, and search quality. There was no significant effect of stimulus or array type on accuracy or time. Figure targets in a higher search quality, suggesting a right hemispheric dominance effect on these tasks. The findings support a d eficit in visuomotor scanning performance in TBI beyond a purely motor effect. Interactions between stimulus and array types suggest that he mispheric cooperation is required for the optimal performance of these tasks, and that interhemispheric communication may be preferentially compromised by TBI.