Decision-making is usually a secondary topic in psychology, relegated to the last chapters of textbooks. Most of the time these chapters acknowledge the failure of the “homo economicus” model and propose to understand human irrationality as the product of heuristic and biases, which may be rational under certain environmental conditions. Psychology pictures decision-making as a deliberative task, studied by multiple-choice tests using the traditional paper and pen method. Psychological research on decision-making assumes that the subjects’ competence in probabilistic reasoning – as revealed by these tests – is a good description of their decision-making capacities. This conception takes for granted (1) that the process of reasoning about action is identical to the process of decision-making and (2) that psychology documents either human failures to comply with rational-choice standards or how mental mechanisms are ecologically rational. In this talk, I argue that decision neuroscience (“neuroeconomics”) may suggest another approach for the study and the nature of decision-making. Research in this field show that information processing in decision is affective, embodied and prosocial: Evolutionary older neural structures, such as the limbic system or dopaminergic neurons, are highly involved in subjective risk and certainty assessment; somatosensory information is integrated in prefrontal areas and helps evaluating choices; In games where players may adopt fair or unfair attitudes, the first ones tend to be more frequent and the second ones elicit emotionally negative reaction.
Moreover, I suggest (against bounded rationality) that these mechanisms achieve near-optimality in social decision-making and (against ecological rationality) that this optimality is not fitness-enhancing. Consequently, I argue that the study of decision-making should be construed as an investigation into “natural rationality” (the mechanisms by which cognitive agents make decisions) and that decision-making should be a central concern for psychology.