The thoughtful and stimulating analysis provided by McKay & Dennett (M&D) on human misbelief is incomplete. Assuming that misbeliefs are products of faulty design features internal to the human organism, M&D have unduly ignored the important role played by the external environment in shaping human action and outcome. This neglect of environmental context holds two crucial implications for their analysis.
First, M&D conclude that positive illusions are adaptive, and thus, the best candidates to be misbeliefs engineered by evolution. In particular, they point to the established, albeit contentious, literature suggesting that positive illusions aid people in their resilience against some of the most extreme challenges of life, such as terminal illness or the aftermath of civil war (cf. Armor & Taylor Reference Armor, Taylor and Zanna1998).
Those studies, however, exist in only one constrained environmental context. Elsewhere, the literature is filled with numerous counterexamples, strewn across business, education, and policy worlds, in which positive illusions prove costly or even disastrous (for reviews, see Dunning Reference Dunning2005; Dunning et al. Reference Dunning, Heath and Suls2004). Some of them even come from the health domain. People treat their own high blood pressure based on mistaken ideas about their competence to do so, setting aside their doctor's orders (Meyer et al. Reference Meyer, Leventhal and Gutmann1985). They smoke, at least in part, because of mistaken beliefs about their ability to avoid serious illness (Dillard et al. Reference Dillard, McCaul and Klein2006). Teenage girls who rate their knowledge about birth control highly, independent of actual knowledge, are more likely to get pregnant within a year relative to their less self-flattering peers (Jaccard et al. Reference Jaccard, Dodge and Guilamo-Ramos2005). Just as a thought experiment, it is easy to come up with numerous contexts in which positive illusions might be the opposite of adaptive. Answer yes or no to the following thought question: When flying, I prefer my pilot to have an overconfident view of his or her ability to handle rough weather.
The point here is that the extant evidence connecting positive illusions to adaptive outcomes is mixed, at best, and depends crucially on the specific environmental context under study. This is not to dismiss those important areas where a positive connection exists; but much more work is necessary to see just how the environmental context, systematically, turns on and off the connection between positive illusion and adaptive outcomes. It may turn out that positive illusions, in the end, bring more sorrow than pleasure. At least it is worthwhile discerning more precisely the circumstances in which that is so.
Such an analysis of environmental context is crucial also to assess M&D's tentative assertion that positive illusions are specifically a product of human evolution. If they are, then they should be more consistently evident in tasks with evolutionary significance (e.g., getting a full belly, achieving reproductive success) than those without. But, to date, that careful analysis across environmental contexts has not been done.
Second, M&D take misbeliefs to be direct evidence of faulty design features in the human organism. That may be the case, but there is an equally compelling case emerging in the psychological literature that it is the environment, not human flaw, that makes these biases unavoidable. Even a perfectly rational human organism could come to hold the types of misbeliefs that M&D discuss, because the environment much more frequently provides people with incomplete or misleading data than M&D anticipate.
In my own work, I have discussed how people might come to hold overly inflated self-views because the environment fails to furnish all the data they need to form accurate self-impressions. In the course of their lives, for example, people decide on actions that they believe are the most reasonable among the choices available. However, when they choose unwisely, they do so because the environment fails to provide the data that would inform them of just how ill-advised their choices are (Dunning Reference Dunning2005). Give them that data and they snap quickly to a more accurate view of themselves (Caputo & Dunning Reference Caputo and Dunning2005; Kruger & Dunning Reference Kruger and Dunning1999).
As another example, take the observation that people tend to view others with suspicion, anticipating much more harm from others than actually is the case (e.g., Duntley & Buss Reference Duntley and Buss1998). M&D speculate that this bias evolved because it protected people from injury, whether physical or psychic. Recent work, however, suggests that the real potential culprit producing this bias is the environment, not a design feature of the human organism.
For example, people tend to be overly cynical about how trustworthy other people are (Fetchenhauer & Dunning Reference Fetchenhauer and Dunning2009). We have recently demonstrated that this cynicism is produced by environmental factors, in that the environment furnishes people with incomplete feedback about their decisions to trust others. When people trust others, their trust is occasionally violated, and people quite rationally move toward a more cynical view of human nature. However, when they mistakenly decide to withhold trust from a person who actually would have honored that trust, they receive no equivalent corrective feedback. Thus, they are left with a unduly wary view of the other individual and of humanity in general. We have shown how furnishing people with complete feedback, including letting people know when their withheld trust would have been honored, rids them quickly of their cynical misbeliefs – and leads them to make trust decisions that provide greater tangible benefits (Fetchenhauer & Dunning, in press; see also Denrell Reference Denrell2005; Smith & Collins Reference Smith and Collins2009).
In sum, M&D have taken first intelligent and careful steps toward an evolutionary treatment of human misbelief, but they need to consider the crucial role played by environmental context before their evolutionary analysis potentially veers into misbelief itself. Social psychologists often chide laypeople in their everyday lives for neglecting the impact of environmental forces on human behavior and outcomes (Nisbett & Ross Reference Nisbett and Ross1980). Thus, as theorists, we should commit to giving environmental forces their due in our own thinking about the human condition.
