Unravelling the many facets of human cooperation in an experimental study

Scientific Reports. 2023. Vol. 13. No. 1. Article 19573.

Rostovtseva V., Puurtinen M., Emiliano Méndez S., Cox R. ., Groothuis A. ., Butovskaya M.

Humans readily cooperate, even with strangers and without prospects of reciprocation. Despite
thousands of studies, this finding is not well understood. Most studies focussed on a single aspect
of cooperation and were conducted under anonymous conditions. However, cooperation is a multifaceted
phenomenon, involving generosity, readiness to share, fairness, trust, trustworthiness, and
willingness to take cooperative risks. Here, we report findings of an experiment where subjects had to
make decisions in ten situations representing different aspects of cooperation, both under anonymous
and ‘personalised’ conditions. In an anonymous setting, we found considerable individual variation in
each decision situation, while individuals were consistent both within and across situations. Prosocial
tendencies such as generosity, trust, and trustworthiness were positively correlated, constituting
a ‘cooperativeness syndrome’, but the tendency to punish non-cooperative individuals is not part
of this syndrome. In a personalised setting, information on the appearance of the interaction
partner systematically affected cooperation-related behaviour. Subjects were more cooperative
toward interaction partners whose facial photographs were judged ‘generous’, ‘trustworthy’, ‘not
greedy’, ‘happy’, ‘attractive’, and ‘not angry’ by a separate panel. However, individuals eliciting
more cooperation were not more cooperative themselves in our experiment. Our study shows that a
multi-faceted approach can reveal general behavioural tendencies underlying cooperation, but it also
uncovers new puzzling features of human cooperation.

Keywords: cooperation