Age-dependent changes in intuitive and deliberative cooperation

Cooperation is one of the most advantageous strategies to have evolved in small- and large-scale human societies, often considered essential to their success or survival. We investigated how cooperation and the mechanisms influencing it change across the lifespan, by assessing cooperative choices from adolescence to old age (12-79 years, N = 382) forcing participants to decide either intuitively or deliberatively through the use of randomised time constraints. As determinants of these choices, we considered participants' level of altruism, their reciprocity expectations, their optimism, their desire to be socially accepted, and their attitude toward risk. We found that intuitive decision-making favours cooperation, but only from age 20 when a shift occurs: whereas in young adults, intuition favours cooperation, in adolescents it is reflection that favours cooperation. Participants' decisions were shown to be rooted in their expectations about other people's cooperative behaviour and influenced by individuals' level of optimism about their own future, revealing that the journey to the cooperative humans we become is shaped by reciprocity expectations and individual predispositions.

Automated summary

Cooperation is an advantageous strategy in human societies, crucial for their success or survival. This study explored how cooperation changes across the lifespan, finding that intuitive decision-making favors cooperation from age 20, while in adolescents, reflective thinking promotes cooperation. Participants' choices were influenced by their expectations of others' cooperative behavior and their level of optimism about their own future, highlighting the role of reciprocity expectations and individual predispositions in shaping cooperative humans.