Personal experience outweighs public reputation when we judge defectors

When a colleague refuses to cover a shift, or a neighbor declines to help with a community project, most of us do not judge that refusal in a vacuum. We weigh what we have heard about the person from others against what that person has actually done to us. A new experimental study led by Professor Hitoshi Yamamoto of Rissho University, published in the journal Evolution and Human Behavior on September 14, 2026, shows that when these two sources of information collide, our own direct experience can override public reputation—particularly when we are judging someone who refused to cooperate.

The research addresses a long-standing puzzle in the science of cooperation. Human societies sustain remarkably high levels of collaboration among genetically unrelated individuals, and one of the most influential theoretical explanations is indirect reciprocity. Under indirect reciprocity, people decide whether to help someone based on that person’s reputation: those known to help others earn a good standing, which makes third parties more willing to assist them in the future, while defectors acquire bad standing and are shunned. Because reputational information circulates socially, an individual can benefit from a good reputation even with people they have never met. Decades of theoretical modeling and behavioral experiments have explored how such reputation-based systems can stabilize cooperation, but most of this work has focused on socially shared information—what everyone in a group supposedly knows about everyone else.

Everyday life, however, rarely presents reputation and experience in neat agreement. A coworker may be widely praised yet have treated you badly, or a neighbor may carry a poor reputation despite having personally helped you when you needed it. Yamamoto and his colleagues set out to examine precisely this conflict: how do people evaluate another person’s decision to cooperate or refuse when the public standing of the individual involved contradicts what the evaluator has directly experienced? The question matters because evaluations are the currency of indirect reciprocity. If people’s judgments are swayed by private history rather than shared reputation, the mechanics of reputation-based cooperation may be more complicated than standard models assume.

To investigate, the team conducted two scenario-based experiments with participants in Japan. The scenarios were deliberately grounded in familiar social settings: one involved coworkers at a restaurant, and the other involved neighbors in a residential community. In each scenario, participants read about a situation in which one person either cooperated with or refused a request made by another person. The researchers systematically varied two factors. The first was the reputation of the person making the request—whether that individual was publicly regarded as good or bad. The second was the participant’s own prior experience with the person responding to the request—whether that responder had previously cooperated with or refused to cooperate with the participant personally. Participants then evaluated the person who had responded, allowing the researchers to measure how reputation and personal experience each shaped moral judgment.

The results revealed a striking asymmetry between cooperation and non-cooperation. When the responder refused the request, evaluations of that refusal depended heavily on the participant’s own prior experience with the responder. Even when the responder carried a bad public reputation, the refusal was judged more negatively if that responder had previously helped the participant. Conversely, even when the responder enjoyed a good reputation, the refusal was judged more positively if that responder had previously refused to help the participant. In other words, when public reputation and personal experience pointed in opposite directions, it was the private, firsthand history that strongly colored how participants rated the act of non-cooperation. The shared social record, which much of the indirect reciprocity literature treats as the decisive input, was effectively pushed aside.

Cooperative behavior told a different story. Acts of cooperation were generally evaluated positively regardless of the other person’s reputation and regardless of how that person had previously treated the participant. This suggests that the human evaluative system does not process cooperation and defection symmetrically. Cooperation appears to be rewarded almost automatically, insulated from the evaluator’s private grievances and from the target’s public standing. Defection, by contrast, invites a more contextualized judgment—one in which the evaluator asks not simply whether the refusal was socially acceptable, but how the person on the receiving end had previously treated them personally.

Perhaps the most sobering finding concerned a scenario in which refusing seemed entirely justified. When the person being refused had both a bad public reputation and a personal history of refusing to cooperate with the participant—conditions under which there appeared to be good reason to withhold help—the refusal itself was still evaluated neutrally rather than positively. Refusing, in other words, was not converted into a virtuous act even when the circumstances seemed to warrant it. This indicates that while people may tolerate or excuse non-cooperation under certain conditions, they do not necessarily celebrate it as positively good. The moral ledger of everyday cooperation appears to reserve its positive marks for helping, with refusal occupying at best a neutral zone even when justified.

From a technical perspective, the findings challenge a simplifying assumption embedded in many formal models of indirect reciprocity. Standard models typically treat reputational information as a single, socially shared signal that determines who deserves help. The new results suggest that human evaluators integrate at least two distinct channels—socially transmitted reputation and privately accumulated experience—and that the weighting between these channels depends on the type of behavior being judged. For defection, the private channel dominates; for cooperation, the evaluation is largely insensitive to either channel. This kind of asymmetric integration could have important consequences for how reputation-based cooperation actually operates in groups, because it implies that shared reputational records may be less powerful in governing sanctions and forgiveness than theorists have often assumed. It also hints at why personal grudges and personal loyalties can persist within communities even when everyone has access to the same public information about one another.

The study also clarifies the scope of previous research. Earlier work on indirect reciprocity concentrated mainly on how socially shared reputational information guides decisions about whom to cooperate with, leaving open the question of what happens when that shared information conflicts with lived experience. By manipulating reputation and personal experience independently within controlled scenarios, Yamamoto and his colleagues were able to isolate the contribution of each source and demonstrate that direct experience is not merely one input among many but can override reputation altogether in judgments of defection. The use of two distinct social contexts—workplace and neighborhood—suggests the pattern is not confined to a single type of relationship, although the scenarios were hypothetical and conducted with participants in Japan, so further work will be needed to test how general the effect is across cultures and real-world interactions.

Professor Yamamoto framed the work as a step toward understanding how people combine heterogeneous information when judging others. “In everyday life, we judge others by combining many different kinds of information, including what we hear about them from others and what we have experienced ourselves,” he said. “Our study provides one clue to understanding how people make judgments when these sources of information do not agree.” He also outlined where the research program is headed next: “In future research, we would like to examine how people use reputational information in environments where direct personal experience is limited, such as online rating systems and AI-mediated judgments.” That direction is increasingly urgent. On digital platforms, ratings and reviews function as public reputations, yet users often have little or no direct experience with the sellers, drivers, or service providers they evaluate. If human judgment naturally privileges firsthand experience where it exists, the design of reputation systems for environments that lack such experience becomes a genuinely open scientific and engineering question—one that this study helps to define.

Subject of Research: How direct personal experience and public reputation interact in human evaluations of cooperation and defection in indirect reciprocity

Article Title: “Public reputation” or “Personal experience”?

Article References: “Public reputation” or “Personal experience”?. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: indirect reciprocity, cooperation, reputation, defection, social evaluation, human behavior, evolutionary psychology, moral judgment, personal experience, scenario experiments, Evolution and Human Behavior, prosocial behavior