Understanding cooperativeness in humans

We report on an experimental study where human subjects (N=176) had to take decisions in ten game-like situations that highlight different aspects of cooperation (generosity, trust, trustworthiness, free-riding, division of labour, coordination, punishment). In a first step, we confirmed earlier findings that individuals differ in “cooperativeness”: there is considerable behavioural variation within each game and the behaviour across games is strongly correlated. As in other experiments with a different set-up generosity, trust, and trustworthiness are positively correlated, and these behavioural tendencies were not correlated with the tendency to punish non-cooperators. In a second step, we investigated whether, when and how individuals behave differently in a “personalized” setting (after having seen a neutral silent video of their interaction partner) than in an anonymous setting. Personalisation did indeed have a systematic effect: our subjects were more cooperative toward interaction partners who, on basis of their face pictures, had been judged generous, trustworthy, not greedy, attractive, happy, and not angry by a separate panel. Hence, the appearance of one’s partner clearly affects behaviour in cooperation games. In a third step, we analysed whether subjects that elicited cooperative behaviour in the personalisation test tended to be more cooperative in the experiment themselves. Here, no clear conclusion could be drawn: the actual cooperativeness of subjects in the games was only weakly and inconsistently correlated to their face judgments by a separate panel and to the behaviour they elicited in the personalisation test