Illusion of explanatory depth

The illusion of explanatory depth (IOED) is cognitive bias or an illusion where people tend to believe they understand a topic better than they actually do. The term was coined by Yale researchers Leonid Rozenblit and Frank Keil in 2002. The effect was observed in only one type of knowledge called explanatory knowledge, in this case defined as "knowledge that involves complex causal patterns" (see causal reasoning). The effect has not been observed in procedural, narrative, or factual (descriptive) knowledge. Evidence of the IOED occurring has been found in everyday mechanical and electrical devices such as bicycles, in addition to mental disorders, natural phenomena, folk theories, and politics, with the most studied effect of IOED being in politics in the form of political polarization.

The illusion is related to the Dunning–Kruger effect, differing in that the IOED examines explanatory knowledge as opposed to ability. Limited evidence exists suggesting that the effects of the IOED are less significant in subject matter experts, but it is believed to affect almost everyone, compared to the Dunning–Kruger effect which is usually defined to apply only to those of low to moderate competence. The IOED is more significant for historical knowledge, in cases when knowing about the topic is perceived as socially desirable.

Another description of the IOED is that "we mistake our familiarity with a situation for an understanding of how it works". IOED has also been suggested to explain the perception that psychology as a field is "simple" or "obvious".