OBJECTIVES: To determine the influence of motivation on performance in a divided attention test of patients after mild traumatic brain injury (MBI). METHODS: Comparison of the performance of 12 patients with MBI with 10 patients with severe brain injury (SBI) and 11 healthy controls in a computer supported divided attention task before (T1) and after (T2) verbal motivation. RESULTS: At T1, the MBI group performed the same as the SBI group but significantly worse than the controls in all variables. At T2, the MBI group performed worse than the controls at T2 but the results were equal to the results of the controls at T1 and significantly better than the SBI group at T1 or T2. At T2 the MBI group performed at the level of published norms for the rest. CONCLUSION: Before verbal motivation the MBI group's results in the divided attention task were comparable with those from patients with severe brain injury. They failed to exploit their performance potential when it depended on self motivation but were able to perform at the level of the control group when external motivation was applied.
