What the Dunning-Kruger Effect Actually Is

Of the 200-some cognitive biases so far identified, the Dunning-Kruger Effect is among the most widely recognized. Although (or maybe because) the effect is widely recognized, people understand what it is in different ways that are, in some ways, contradictory. For example, there are graphs claiming to represent the Dunning-Kruger Effect, depicting overconfidence as a function of competence, and noting features such as "Mt. Stupid" and the "Plateau of Sustainability."

In this post I explain what the Dunning-Kruger Effect actually is, beginning with a brief summary of it. In 1999, Justin Kruger and David Dunning described an experiment that demonstrated what has become known as the Dunning-Kruger Effect. [Kruger & Dunning 1999] They found that when we assess our own competence or abilities in a particular field, or relevant to a particular task, we tend to commit systematic errors. Later experiments by Dunning, Kruger, and others have shown that the effect appears when making assessments of performance either in an absolute sense, or relative to others. Some controversy about interpretation of their data does remain, but most observers agree that the result is useful. [Dunning 2011] [Gignac & Zajenkowski 2020]

Still, there is some disagreement about how to express their result. As Dunning puts it, people tend to be ignorant of their own ignorance. Moreover, analogous errors appear when assessing others' performance. Briefly, there are limits to the accuracy of any assessment of someone's performance in a given field, or with respect to a given task. The accuracy of the assessment is limited by the assessor's own competence in that field, or with that task. This general principle has four specific expressions:

• The less competent tend to overestimate their own competence
• The less competent don't recognize the superior competence of the more competent
• The more competent tend to underestimate their own relative competence
• The more competent tend to estimate accurately the incompetence of the less competent

Example misstatements of the Dunning-Kruger Effect

In numerous white The accuracy of any assessment of someone's
competence with respect to a task is limited by
the assessor's own competence with that taskpapers and journal articles, the Dunning-Kruger Effect is restated or summarized in various ways. But the restatements and summaries aren't always consistent with the work of Dunning and Kruger. Below are two examples of restatements of the Dunning-Kruger Effect that are not aligned with what Dunning and Kruger actually found. In what follows I use the term subject to refer to the person who is assessing someone else's performance.

Restatement: "Dunning-Kruger is where overconfidence blinds subjects to their own limitations"

This recasting of the Dunning-Kruger Effect implies that overconfidence makes the subject's incompetence invisible to the subject. Contrast this view to that of Dunning and Kruger, who state that limitations of the subject's in-field competence, among other factors, is what makes the subject's incompetence invisible to the subject.

This is an important distinction. In Dunning and Kruger's model, enhancing the subject's competence is one way to address the metacognitive error. In the recasting, there is no indication that enhancing the subject's competence would improve the assessor's accuracy. Overconfidence is not the cause of the error; it is the result.

Restatement: "Subject has an inflated self-perception"

In this model of the Dunning-Kruger Effect, the root cause of the metacognitive error is some kind of flaw in the subject's character that somehow creates an inflated perception of the self. On the part of its proponents, this model might actually serve as an example of the Fundamental Attribution Error. An alternative form of this misrepresentation of the Dunning-Kruger Effect is "subjects refuse to acknowledge limitations due to inflated ego."

Interventions guided by this way of understanding the Dunning-Kruger Effect would tend to emphasize interpersonal skill development, or possibly psychotherapeutic approaches. On the other hand, Dunning and Kruger would tend to emphasize enhancing competence in the relevant field or task.

Last words

An irony associated with the Dunning-Kruger Effect might now be clear. It is possible for someone to assess their own understanding of the Dunning-Kruger Effect as more accurate than it actually is. That is, their ability to assess their grasp of the effect is limited by their grasp of the effect. As they put it:

Although we feel we have done a competent job in making a strong case for this analysis, studying it empirically, and drawing out relevant implications, our thesis leaves us with one haunting worry that we cannot vanquish. That worry is that this article may contain faulty logic, methodological errors, or poor communication. Let us assure our readers that to the extent this article is imperfect, it is not a sin we have committed knowingly.

Dunning and Kruger recognized this paradoxical possibility and included the above paragraph in the closing words of their 1999 paper — a courageous step indeed. I, too, might be committing the same error herein. Scary.  Top    Next Issue

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