How do I practice overconfidence bias?

The most direct way to practice overconfidence bias is through a focused exercise: Run a ten-question calibration test on yourself right now. For each question, estimate a numerical range you are 90% confident contains the true answer. Use questions with verifiable answers: the population of Brazil, the height of the Eiffel Tower in meters, the year the first iPhone was released, the distance from Earth to Mars in kilometers at closest approach, the number of bones in the adult human body, the GDP of Japan in trillions of USD, the boiling point of ethanol in Celsius, the length of the Nile River in kilometers, the number of symphonies Beethoven composed, the speed of sound in meters per second at sea level. Write your ranges before looking anything up. Then verify each answer. Count how many of your 90% confidence intervals contained the true value. If you are well-calibrated, nine out of ten should. If you are typical, four to six will. The gap between your target (90%) and your hit rate is your overconfidence score. That number is the size of the problem this lesson addresses.

Common pitfall: Believing you are the exception. The most insidious feature of overconfidence is that it includes confidence in your own calibration. The person who reads about overconfidence bias and thinks "interesting, but I am pretty well-calibrated" is demonstrating the bias in real time. Overconfidence is not a bias that affects other people while sparing you. It is the default setting of human cognition. The only known partial remedy is structured feedback — which is why this lesson sits between L-0142 (calibration requires feedback) and L-0144 (track your predictions). Without the tracking system you will build tomorrow, the insight from today will decay into exactly the kind of abstract knowledge that overconfident people mistake for operational skill.

This practice connects to Phase 8 (Perceptual Calibration) — building it as a repeatable habit compounds over time.