When the Journal of Personality and Social Psychology (JPSP) compiled a list of the papers most often cited in its pages, the salutatorian was not a JPSP article (nor was the valedictorian, but that is another story). Nor was it even a social psychology article – at least not exclusively (Quinones-Vidal et al. Reference Quinones-Vidal, Lopez-Garcia, Penaranda-Ortega and Tortosa-Gil2004). It was Taylor and Brown's (1988) review of “Positive Illusions,” the series of biases that McKay & Dennett (M&D) nominate as one of the “best candidates for evolved misbelief” (target article, sect. 13).

And for good reason (both the citation count and nomination). Taylor and Brown (Reference Taylor and Brown1988) not only advanced a compelling argument as to why some judgmental biases might actually be healthy (an argument equally compellingly taken to its logical extreme by the target article), but also provided an elegant summary of the various ways in which people see themselves and the world around them in an unrealistically favorable light. People overestimate how their traits and abilities stack up against those of others. They believe that their futures are rosier than those of the average person. And they believe that they control what they do not. Collectively, these “positive illusions” instantly rang true for both psychologists and laypeople alike, corroborating both common wisdom and an idea as old as psychology itself (Freud Reference Freud and Strachey1920; Roese & Olson Reference Roese and Olson2007). Indeed, so intuitive is the insight that it is hard for most of us even to imagine a time in which it could have been controversial, but indeed it once was (Festinger Reference Festinger1954). As we now know, “most people view themselves as better than average on almost any dimension that is both subjective and socially desirable” (sect. 13, para. 2).

The problem, to paraphrase the opening quote, is that sometimes what we know just ain't so.

Consider what is perhaps the best-known illustration of the “above-average effect,” from the College Board Survey (1976–77). When 828,516 high-school students taking the SAT were asked about their leadership ability, 70% claimed to be “above-average” and only 2% “below-average.” When asked about their “ability to get along with others,” 89% reported that they were above-average, fewer than 0.5% admitted to being below-average, and a full 25% reported being in the top first percentile.

One could point out that the results are misleading, and they are most certainly that. For one, the students may have felt pressured to present themselves in a favorable light. The questions, after all, were being asked by the same people determining their suitability for college. For another, the colloquial definition of “average” is considerably gloomier than the dictionary definition. Most of the students, therefore, could very well have been above-average – at least by their construal of the term. Even by the mathematical definition the sample may have been above-average. The sample, although large, was comprised exclusively of high-school students taking the SAT, the majority of whom could have very well been better leaders and more of the “get-along-with-others” type than the average high-school student (this is even possible with a representative sample if the distribution of performance is sufficiently skewed, but never mind that).

All of these are reasons to question the results of the College Board Survey and the many others like it. They are not the reasons to doubt the existence of positive illusions such as the “above-average effect,” however, because the effect replicates even when the above factors are accounted for (e.g., Kruger & Burrus Reference Kruger and Burrus2004; Dunning et al. Reference Dunning, Meyerowitz and Holzberg1989). Nor even is the reason for doubt the fact that the above-average effect and unrealistic optimism often fail to replicate in “collectivist” cultures such as those found in East Asia, South America, and the Middle East (Heine et al. Reference Heine, Lehman, Marcus and Kitayama1999; Henrich et al., in press).

Instead, the reasons for doubt are the many instances in which healthy populations exhibit, not positive illusions, but systematic negative ones. In the case of the above-average effect, although people overestimate their ability relative to others on easy tasks, such as using a computer mouse or riding a bicycle, they tend to underestimate their ability on difficult tasks, such as programming a computer or telling a really good joke (Kruger Reference Kruger1999; Moore Reference Moore2007). Similarly, although college students believe that they are more likely than the average student to experience common desirable events such as getting a job with a starting salary over $25,000 or living past 70, they believe that they are less likely than the average person to land a salary over $250,000 or live past 100 – despite the fact that the latter are at least as desirable as the former (Kruger & Burrus Reference Kruger and Burrus2004).Footnote ¹

Indeed, for virtually every social comparison bias one might label “positive illusion” there appears to be a complementary “negative illusion.” People overestimate their likelihood of beating a competitor when the contest is simple (such as a trivia contest involving easy categories), but underestimate those odds when it is difficult (such as a trivia contest involving difficult categories; Moore & Kim Reference Moore and Kim2003; Windschitl et al. Reference Windschitl, Kruger and Simms2003). Roommates overestimate their relative contribution to tasks involving frequent contributions like cleaning the dishes, but underestimate their relative contribution to tasks involving infrequent contributions like cleaning the oven (Kruger & Savitsky Reference Kruger and Savitsky2009). And preliminary work suggests that although people overestimate their degree of control over that which can be controlled easily, they underestimate their degree of control of what cannot (Kruger, unpublished data).

That said, it would be misleading to suggest that these results imply that, ecologically speaking, negative illusions outnumber positive ones. The above research does not speak to this question, nor is it an easy – or perhaps even possible – question to answer. What the research does suggest, however, is that there is reason to question the assumption that positive illusions are the norm for healthy individuals. It may be one of those “things we know that just ain't so” (Artemus Ward, as cited in Gilovich Reference Gilovich1991). It is perhaps worth noting that it was likely not Artemus Ward who said those words, but instead the late humorist Josh Billings.Footnote ²