optimismebias

Optimism bias, or optimismebias, is a cognitive bias in which people overestimate the likelihood of positive events for themselves and underestimate the likelihood of negative events in the future. It reflects miscalibration of personal risk.

It is widely studied in psychology and behavioral economics and has been observed across domains such as health, finances, safety, and career planning. It is related to concepts such as unrealistic optimism.

Mechanisms include information asymmetry about one’s own situation, mood and motivation, and cognitive heuristics that favor favorable interpretations. People may focus on hopeful outcomes and discount adverse data.

Examples: underestimating the chance of illness, overestimating future income, or assuming personal safety is higher than base rates justify.

The bias can promote persistence and well-being but also lead to inadequate preparation, risk-taking, and postponed warning signs.

Measurement often compares perceived probabilities for oneself with base-rate data or with probabilities assigned to others. Mitigation includes premortem exercises, red-teaming, basing decisions on base rates, and prompting consideration of worst-case scenarios.

Related terms include unrealistically optimistic risk perception.