Altruism (a costly action that benefits others) and reciprocity (the repayment of acts in kind) differ in that the former expresses preferences about the outcome of a social interaction, whereas the latter requires, in addition, ascribing intentions to others. Interestingly, an individual’s behavior and neurophysiological activity under outcome- versus intention-based interactions has not been compared directly using different endowments in the same subject and during the same session. Here, we used a mixed version of the Dictator and the Investment games, (...) together with electroencephalography, to uncover a subject’s behavior and brain activity when challenged with endowments of different sizes in contexts that call for an altruistic (outcome-based) versus a reciprocal (intention-based) response. We found that subjects displayed positive or negative reciprocity (reciprocal responses greater or smaller than that for altruism, respectively) depending on the amount of trust they received. Furthermore, a subject’s late frontal negativity differed between conditions, predicting responses to trust in intentions-based trials. Finally, brain regions related with mentalizing and cognitive control were the cortical sources of this activity. Thus, our work disentangles the behavioral components present in the repayment of trust, and sheds light on the neural activity underlying the integration of outcomes and perceived intentions in human economic interactions. (shrink)

From an evolutionary perspective, phenotypic, social, and environmental factors help to shape the different costs and benefits of pursuing different reproductive strategies from one individual to another. Since men’s reproductive success is mainly constrained to women’s availability, their mating orientations should be partially calibrated by features that women prefer in a potential partner. For long-term relationships, women prefer traits that signal access to resources, protection skills, and the willingness to share them. Using generalized linear models with laboratory data taken from (...) a Chilean population, this study aimed to test whether real and potential resources, protection skills, and the willingness to provide resources and protection are related to mating orientation in men. Our predictions were: socioeconomic status would be positively associated with long-term and short-term mating orientation but for long-term-oriented individuals, this would be enhanced by having a more favorable parenthood disposition and strength would be positively related to long-term mating orientation in men with higher socioeconomic status and a favorable disposition toward parenthood and it would have a positive and direct association with short-term mating orientation. Our results partially supported the first hypothesis, since men with higher socioeconomic status were more long-term oriented, but parenting disposition did not moderate this effect. Contrary to our expectations, socioeconomic status was not related to short-term mating orientation. Strength appeared not to be significant for long-term mating orientation, even interacting with other traits. However, strength by itself was powerfully linked with a short-term mating orientation. Our results suggest that only some individuals that are attractive for long-term relationships are indeed long-term oriented and may reflect the overall conflict of interests between mating strategies among sexes. (shrink)