Making decisions and advising decisions in traumatic brain injury.

Objective: Decision under ambiguity and decision under risk are fundamental in every-day life.

Methods: We investigated these 2 types of decision in traumatic brain injury (TBI) patients through the Iowa Gambling Task (IGT), the Probability-Associated Gambling (PAG) task, and a counsel version of the PAG task. Although in the IGT rules for gain and losses are implicit and probability information is missing, in the PAG task and the counsel task rules are explicit and probabilities are well-defined.

Results: In the IGT, TBI patients selected more disadvantageously than healthy controls and failed to develop an advantageous strategy over time. Patients also made less advantageous choices than controls in the PAG task and the counsel task. Compared with controls, TBI patients gambled more frequently with low probabilities and less frequently with high probabilities. Overall, participants decided more advantageously in the counsel task, which does not provide feedback, than in the PAG task. Importantly, our results indicate that TBI patients' performance on all decision tasks correlated with executive functions.

Conclusions: Our study shows that TBI patients have difficulties in decision under risk and decision under ambiguity. Difficulties may be attributed to deficient learning from feedback and to reduced risk estimation, but not to impulsive risk taking behavior.