Divided Attention After Closed Head Injury

One of the most persisting sequelae of closed head injury (CHI) is a general slowing of information processing. With neuropsychological testing, the effect is already apparent in simple reaction time tests. The slowing is more pronounced in complex tasks requiring divided attention. This study aims at explaining impairments in divided attention in terms of reduced speed of information processing, and impaired mental flexibility. Three types of mental flexibility are proposed: Stimulus driven (four choice reaction time and auditory reaction time task), memory driven (Trailmaking B test), and strategy driven flexibility tasks (continuous tracking task and arrow identification task). Divided attention paradigms were studied in 26 subacute CHI patients and 25 orthopedic control subjects. Results demonstrated that a reduced speed of information processing was largely responsible for divided attention impairments. Additional impairments in complex divided attention tasks only emerged in the most complex tasks (that is in the strategy driven flexibility task).