The Dunning–Kruger Effect: On Being Ignorant of One’s Own Ignorance

In this chapter, I provide argument and evidence that the scope of people’s ignorance is often invisible to them. This meta-ignorance (or ignorance of ignorance) arises because lack of expertise and knowledge often hides in the realm of the “unknown unknowns” or is disguised by erroneous beliefs and background knowledge that only appear to be sufficient to conclude a right answer. As empirical evidence of meta-ignorance, I describe the Dunning– Kruger effect, in which poor performers in many social and intellectual domains seem largely unaware of just how deficient their expertise is. Their deficits leave them with a double burden—not only does their incomplete and misguided knowledge lead them to make mistakes but those exact same deficits also prevent them from recognizing when they are making mistakes and other people choosing more wisely. I discuss theoretical controversies over the interpretation of this effect and describe how the self-evaluation errors of poor and top performers differ. I also address a vexing question: If self-perceptions of competence so often vary from the truth, what cues are people using to determine whether their conclusions are sound or faulty? Allow me to begin this chapter with a stipulation that I hope will not be too controversial. That stipulation is that people conduct their daily affairs under the shadow of their own inevitable ignorance. People simply do not know everything about everything. There are holes in their knowledge, gaps in their expertise. I, for example, can name many areas in which my knowledge is incomplete, if it even begins at all. I am not up on the latest developments in hydrostatics and hydraulic circuitry design. I do not know much about the highlights of twentieth century Zimbabwean sculpture. I am not your “go to” guy when it comes to good restaurants in Düsseldorf, Germany. Of course, one might concede the inevitability of ignorance, but argue that most—if not all—of people’s ignorance covers obscure topics that carry no implications for their everyday lives. Much like ants fail to suffer because they do not know, or even conceive of, such topics as bebop jazz or quantum mechanics, people may not suffer because the topics they fail to know fall well beyond the issues that actually influence their outcomes in life. Economists, for example, have argued that most ignorance is rational, in that there are several topics for which gaining expertise would just not provide the tangible benefit to make it worthwhile (Downs, 1957). The Dunning-Kruger Effect 249 1. Two Assertions About Ignorance But I believe this stance toward ignorance is mistaken. Instead, I wish to make two assertions about people’s inevitable ignorance that makes it a quite relevant issue for their daily lives. Of course, making those assertions convincingly takes some argumentation and, more importantly, data. 1.1. Ignorance is prevalent in everyday life First, I wish to argue that the boundary where people’s knowledge ends and their ignorance begins frequently arrives far sooner than one would expect. That boundary often insinuates itself well within the geography of everyday tasks that determine whether people live happy and effective lives—certainly within the circle of challenges that people typically face over the course of a lifetime. For example, in contemporary society, people must filter a good deal of news about scientific facts on such important issues as the environment, medical treatment, and biotechnology. In that regard, the National Science Foundation, in its biannual survey of scientific knowledge, finds large gaps in the basic facts of what people know. In its 2008 survey of roughly 1500 United States adults, only about 53% of respondents knew that electrons are smaller than atoms and only 51% could successfully identify that it was the earth that revolved around the sun (rather than the other way around), taking a year for the earth to do it. When asked whether it was better to test a new high blood pressure drug by giving it (a) to 1000 participants or (b) to 500 participants, with an additional 500 receiving a placebo, only 38% gave the correct answer with an appropriate rationale (National Science Board, 2010). But perhaps science is not a day-to-day activity for typical citizens, so they can be excused for not having basic knowledge about topics they make no direct decisions about. They do, however, make decisions in every election; thus, it is important for citizens to have a basic working knowledge of their government. In a 2009 survey of roughly 2500 American citizens, only half of respondents could name all three branches of the Federal government, only 54% knew that the power to declare war rests with Congress rather than the President, and only 57% could properly identify the role played by the electoral college, with many thinking it “trains those aspiring for higher office” or “supervised the first television debates” (Intercollegiate Studies Institute, 2008). 1 For a response to be coded as accurate, the respondent must provide an appropriate rationale. Many respondents opt for the placebo group, but do so, for example, to keep the fatality rate down if the drug should prove deadly. This is not coded as accurate (Miller, 1998).