Review TRENDS in Cognitive Sciences Vol.11 No.1 Perception and misperception of bias in human judgment Emily Pronin Department of Psychology, Princeton University, Green Hall, Princeton, NJ 08540, USA Human judgment and decision making is distorted by an outcomes and to disregard evidence that threatens their array of cognitive, perceptual and motivational biases. self-esteem. Recent evidence suggests that people tend to recognize Despite the well-documented role of self-enhancement (and even overestimate) the operation of bias in human (or ego-protective) bias in human judgment, people rarely judgment – except when that bias is their own. Aside recognize their susceptibility to it. Although they rate from the general motive to self-enhance, two primary themselves as ‘better than average’ on a wide range of sources of this ‘bias blind spot’ have been identified. traits and abilities, most people also claim that their overly One involves people’s heavy weighting of introspective positive self-views are objectively true [10,11]. Moreover, evidence when assessing their own bias, despite the their unwarranted claims of objectivity persist even when tendency for bias to occur nonconsciously. The other they are informed about the prevalence of the bias and involves people’s conviction that their perceptions invited to acknowledge its influence [11]. In another exam- directly reflect reality, and that those who see things ple, people are biased to make themselves feel better after differently are therefore biased. People’s tendency to negative things happen to them (from heartbreaks to job deny their own bias, even while recognizing bias in rejections) but they are unaware of this ego-protective bias. others, reveals a profound shortcoming in self-aware- Instead, they predict that these negative outcomes will ness, with important consequences for interpersonal leave them feeling bad far into the future [12,13]. and intergroup conflict. People are not similarly resistant to detecting the influ- ence of self-enhancement bias on others. They anticipate Introduction that their peers will make overly positive trait assessments People are not always accurate and objective at perceiving [14]. They also expect others to make self-serving claims of themselves, their circumstances and those around them. responsibility [15]. Indeed, marital partners overestimate People’s perceptions can be biased by their beliefs, expec- the degree to which their spouses will self-servingly take tations and context, as well as by their needs, motives and credit for good outcomes (such as resolving relationship desires [1–3]. Such biases have important consequences. conflicts) and deny credit for bad outcomes (such as break- They can compromise the quality of human judgment and ing household items) [15]. decision making, and they can cause misunderstanding In one experiment, participants assessed their own and and conflict [4–7]. a peer’s self-serving bias in a single situation. They took a Accumulating research shows that people recognize the purported test of social intelligence, and displayed the existence, and the impact, of many of the biases that affect classic bias – those who were told they performed well human judgment and inference. However, they seem to claimed that the test was more valid than those who were lack recognition of the role that these same biases have in told that they performed poorly. However, after being shaping their own judgments and inferences. Here, I informed about the potential for bias in their claims, describe recent evidence of a broad and pervasive tendency participants were more likely to acknowledge that possi- for people to see the existence and operation of bias much bility in their fellow participant than in themselves [11]. more in others than in themselves. In addition to reviewing evidence for this ‘blind spot’ in bias perception, I describe Self-interest biases the psychological processes underlying it. Discussions of bias in public discourse often focus on concerns about the impact of self-interest on others’ judg- Perceptions of bias in self versus others ments and actions. Indeed, it is a common assumption that Self-enhancement biases human behavior is guided by people’s tendency to make Perhaps the most well-known form of bias involves people’s judgments based on what best serves their self-interest inclination to see themselves in a positive light, even when (whether that interest is, for example, financial or political) the evidence suggests otherwise [8]. When people lack [16]. talent or ability, they tend not to notice [9]. They also tend Although people view self-interest as essential for to see their futures as overly rosy, to see their traits motivating human behavior, they view it as a more crucial as overly positive, to take too much credit for successful motivator of others than of themselves. They assume that people who work hard at their jobs are motivated by Corresponding author: Pronin, E. ([email protected]). external incentives such as money, whereas they claim Available online 28 November 2006. that they personally are motivated by internal incentives www.sciencedirect.com 1364-6613/$ – see front matter ß 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.tics.2006.11.001 38 Review TRENDS in Cognitive Sciences Vol.11 No.1 such as feeling a sense of accomplishment [17]. In another in themselves [28]. Similarly, people do not recognize the study [18], students predicted their own and their peers’ influence on themselves of the hindsight bias (i.e. the bias likely contributions to an upcoming charity drive. They to judge historical facts as being more likely to have made unduly positive predictions about their own future occurred after knowing that they occurred) [29]. Moreover, generosity but not about that of their peers, suggesting although people deny the effect of irrelevant but salient that they were more prone to anticipate self-interest in numerical anchors on their numerical estimates, they others’ behavior than in their own. Indeed, people some- claim that others are not similarly immune to this bias times overestimate the impact of others’ susceptibility to [30]. self-interest. In other experiments, college students’ plans As with the anchoring effect, one of the most well-known to donate blood were unaffected by whether they would be biases in social judgment also involves the unwarranted paid, and their attitudes about a campus keg ban were impact of salient information. It involves the tendency for unaffected by whether the ban would impact on their social people’s impressions of others to be colored by salient life. However, in both cases, they assumed that their peers’ situational factors [8,31]. People anticipate this bias in actions and attitudes would be affected by self-interest those around them but not in themselves. In several [19]. experiments, participants delivered speeches expressing Assumptions of self-interest in others, combined with an opinion that was assigned to them. They expected that a denials of it in the self, occur in settings where they can be peer would assume this to be their true opinion, even costly. Physicians recognize that other doctors are suscep- though they knew that the peer was fully aware that it tible to the biasing effects of gifts from pharmaceutical had been assigned to them [32–34]. Moreover, they representatives but they think that they personally resist expected that their peers would show this bias more than these effects [20]. In market settings, sellers perceive their they expected that they themselves would show it [33]. wares as being objectively worthy of a higher price than do buyers, and both assume that any disagreement over price Direct demonstration of a bias blind spot is a function of the greedy self-interest of the other side A final set of studies provides direct evidence for a bias [21]. blind spot [11]. Participants read descriptions of a range of biases (e.g. self-interest, dissonance reduction and biased Prejudice and group-based biases assimilation) and assessed their relative susceptibility to People’s stereotypic beliefs about other groups, and their each one. College students reported being less susceptible affiliations with their own ingroups, color their perceptions than the ‘average American’ to each bias, and they also and judgments. People show subtle (and not so subtle) reported less susceptibility than their peers in a seminar biases in how they perceive and treat members of stigma- class. Moreover, travelers at an international airport tized groups ranging from racial minorities to the over- reported showing the biases to a lesser extent than others weight [8,22]. Even when differences between groups are at the airport that day. minimal and trivial, people tend to favor ingroups over outgroups. Roots of the bias blind spot People generally believe that they are immune to group- Biases are generally viewed as being undesirable. For this based biases. They claim freedom from racial bias, and reason, it is tempting to assume that people’s denials of from gender bias, even in circumstances where they have bias reflect the well-documented self-enhancement motive shown these biases [22,23] – at times even showing these [8,35]. Indeed, there is at least some evidence that people biases more strongly the more objective they claim to be are more likely to acknowledge their susceptibility to [23]. When making judgments about who is ‘right’ in a biases that are less undesirable [11]. Although having a conflict, people tend to side with the person who shares bias blind spot probably contributes to a generally positive their ingroup identity but they again deny that bias [24]. view of the self, numerous research findings now make People can also be blind to forms of group-based bias other clear that the blind spot cannot be understood entirely in than prejudice. For example, although people’s political these terms.