Stop Fooling Yourself! (Diagnosing and Treating Confirmation Bias).

Confirmation bias (CB) is a cognitive bias that allows us to fool ourselves by selectively filtering data and distorting analyses to support favored beliefs or hypotheses. In this article, I will briefly review some classic experiments from cognitive psychology that illustrate what a powerful, pernicious, and insidious force CB is. I will then discuss how to recognize CB in our own thinking and behavior and describe specific elements of good experimental design that can mitigate its effects. These elements-such as randomization and blinding-are conceptually straightforward but often difficult in practice and therefore not as widely implemented as they should be.