Social Decision Making in Adolescents and Young Adults: Evidence From the Ultimatum Game and Cognitive Biases.

During adolescence and early adulthood, individuals deal with important developmental changes, especially in the context of complex social interactions. Previous studies demonstrated that those changes have a significant impact on the social decision making process, in terms of a progressive increase of intentionality comprehension of others, of the sensitivity to fairness, and of the impermeability to decisional biases. However, neither adolescents nor adults reach the ideal level of maximization and of rationality of the homo economicus proposed by classical economics theory, thus remaining more close to the model of the "bounded rationality" proposed by cognitive psychology. In the present study, we analyzed two aspects of decision making in 110 participants from early adolescence to young adulthood: the sensitivity to fairness and the permeability to decisional biases (Outcome Bias and Hindsight Bias). To address these questions, we adopted a modified version of the Ultimatum Game task, where participants faced fair, unfair, and hyperfair offers from proposers described as generous, selfish, or neutral. We also administered two behavioral tasks testing the influence of the Outcome Bias and of the Hindsight Bias in the evaluation of the decision. Our behavioral results highlighted that the participants are still partially consequentialist, as the decisional process is influenced by a complex balance between the outcome and the psychological description of the proposer. As regards cognitive biases, the Outcome Bias and the Hindsight Bias are present in the whole sample, with no relevant age differences.