The social transmission of optimism

The human tendency toward optimism is a fundamental aspect of future thinking, yet how social interaction modulates this bias remains unclear. We investigated whether collaborative future imagination influences individual optimism and its computational underpinnings. Participants engaged in either individual or collaborative prospection, interspersed with likelihood estimations of future events related or unrelated to the imagined scenarios. Collaborative imagination selectively increased optimism bias for related future events. This effect was driven by a social prediction error mechanism, whereby individuals updated their beliefs based on discrepancies between their own optimism and peers’ inferred beliefs. This cognitive update was content-specific and distinct from parallel emotional contagion effects. These findings demonstrate that optimism bias is a malleable, socially transmissible state shaped dynamically by interaction, highlighting a computational mechanism by which social contexts influence prospective cognition.