ABSTRACT
Trust and cooperation are hallmarks of our species, yet they challenge the economic canon of self-interest, especially in situations where it is possible to free-ride on the efforts of others. How do people solve the recurring dilemma of having to choose between personal gain versus mutually beneficial, but risky acts? Much research in economics and psychology has addressed the role of incentives that increase the willingness to cooperate, social cues that allow a person to construe expectations of others, and, from a biological perspective, the neural correlates of decision making and the neurochemicals that affect the decision-making process by altering physiology.
This chapter discusses the results of experiments to show how a multi-method, interdisciplinary approach can improve our understanding of decision-making in social dilemmas. First, behavioral experiments that compare individual decisions in situations that manipulate the presence of incentives and social cues are essential to define the contingencies of trust and cooperation, i.e., to delineate the circumstances under which they are likely to emerge. These experiments show that, when incentives to cooperate are absent, a cooperative decision can still be triggered by cues of trustworthiness, at least for those individuals who hold prosocial values. Second, hormone administration studies can reveal some of the causal physiological underpinnings of decisions. The neuropeptide oxytocin in particular is increasingly studied in this respect because of its known stress reduction functions by which it could remove social apprehension and facilitate social approach behaviors like trust and cooperation. Third, neuroim-aging studies (fMRI) indicate which areas of the brain show increased metabolic activity at the time of decision making. While these data are correlational, when combined with behavioral experiments and hormone administration, fMRI can be a powerful tool to uncover brain mechanisms involved in cooperation, and to corroborate that these mechanisms differ depending on when, and why, people decide to cooperate.
The field of social neuroeconomics relies on all these approaches. Its merit is illustrated in a multi-method experiment that tests the hypothesis that cooperative and competitive decisions are the result of integrating contextual information regarding incentives with contextual information regarding the valence of peripheral social cues. Oxytocin modulates brain activity during 78decision making depending on context, by which it helps to achieve ecologically rational decisions that lead to either cooperation, or competition, when it is desired and warranted.
