Optimism Bias
Type: Cognitive Bias
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Definition
Believing we’re less likely to experience negative events and more likely to experience positive events than others.
Tali Sharot’s research: 80% of people rate themselves as above-average drivers. Most underestimate divorce rates, cancer risks, job loss likelihood.
Why It Matters
Health: Smokers underestimate lung cancer risk. People skip screenings. Finance: “I’ll beat the market.” Most don’t. Planning: Projects take longer, cost more than expected. Relationships: “We’ll never divorce” — 40-50% do.
But also: Necessary for action. Without optimism, we’d never start companies, marry, or have children.
The Trade-off
| Optimism | Pessimism |
|---|---|
| Start businesses | Avoid failure |
| Take risks | Prepare for problems |
| Recover from setbacks | Realistic planning |
| Better health outcomes | Less disappointment |
Realism is the goal — informed optimism, not blind hope.
Fighting Over-Optimism
- Reference class — What happened to others like me?
- Pre-mortem — Imagine failure, work backwards
- Outside view — What would others predict?
- Track predictions — Calibrate over time
Related Biases
- [[Planning Fallacy** — Optimism about timelines
- [[Overconfidence Effect** — Optimism about abilities
- [[Illusion of Control** — Optimism about influence
Audio
Podcast episode: Optimism Bias
Part of the Cognitive Bias Reference