Hard–easy effect

The hard–easy effect is a cognitive bias that manifests itself as a tendency to overestimate the probability of one's success at a task perceived as hard, and to underestimate the likelihood of one's success at a task perceived as easy. The hard-easy effect takes place, for example, when individuals exhibit a degree of underconfidence in answering relatively easy questions and a degree of overconfidence in answering relatively difficult questions. "Hard tasks tend to produce overconfidence but worse-than-average perceptions," reported Katherine A. Burson, Richard P. Larrick, and Jack B. Soll in a 2005 study, "whereas easy tasks tend to produce underconfidence and better-than-average effects."

The hard-easy effect falls under the umbrella of "social comparison theory", which was originally formulated by Leon Festinger in 1954. Festinger argued that individuals are driven to evaluate their own opinions and abilities accurately, and social comparison theory explains how individuals carry out those evaluations by comparing themselves to others.

In 1980, Ferrell and McGoey called it the "discriminability effect"; in 1992, Griffin and Tversky called it the "difficulty effect".