Can psychological labels influence the decision-making process in an unfair condition? Behavioral and neural evidences using the ultimatum game task

The manipulation of the proposer's description in the ultimatum game (UG) using mentalistic labels might influence the final decision along with the sensitivity toward fairness. The present study aimed to investigate neural changes related to the mentalistic description of the proposer in the UG task. For this purpose, 21 healthy adults played the UG task for real during a functional MRI session. According with previous evidence, we considered the responder's behavior to unfair offers in an UG paradigm, in which proposers were described as generous, selfish and neutral. Our results showed that the mentalistic labels significantly influence the acceptance rate; however, no significant differences emerged with respect to the response time. At the neural level, we observed activation of the dorsolateral prefrontal cortex, a brain region involved in the theory of mind network. The mentalistic labels did not result in changes of the neural network activated in the unfair condition during the UG task, except for the level of activation within the cingulate cortex. Particularly, the most incoherent situation where a generous proposer made an unfair offer was associated with a greater activation of the posterior cingulate cortex, an area involved in maintaining a state of vigilance and attention. These results support the idea that the posterior cingulate cortex and the dorsolateral prefrontal cortex are coinvolved when dealing with incoherent situations due to different mentalistic features of the proposer in the UG task.