Sensitivity to fairness and intentions of others in the ultimatum game in patients with ventromedial prefontal lesions

Abstract This study aimed to examine the relationship between perspective-taking and impaired decision-making in patients with ventromedial prefrontal (VM) lesions, using the Ultimatum Game (UG). In the UG, two players split a sum of money and one player proposes a division while the other can accept or reject this. Eight patients with VM damage and 18 healthy controls participated as responders in a modified version of the UG, in which identical offers can generate different rejection rates depending on the other offers available to the proposer. Participants had to either accept or reject offers of 2:8 NIS (2NIS for them and 8 NIS for the proposer), which were paired with one of four different possible offers (5:5, 4:6, 2:8, 8:2). Results indicate that the controls more often rejected offers of 2:8 when the alternative was 4:6 (a greedy alternative) than when the alternative was 5:5 (fair alternative), whereas the VM patients showed the opposite pattern of decision-making. Additionally, the overall rejection rates were higher in patients as compared to controls. Furthermore, scores on a perspective-taking scale were negatively correlated with rejection rates in the patient group, suggesting that perspective-taking deficits may account for impaired decision-making in VM patients. (JINS, 2012, 18, 952-961)