How the Mind Misjudges: A Path Through Reasoning Biases

An arbitrary starting number is enough to pull later estimates toward it, and the adjustment away from it is usually too small. Tversky and Kahneman gave the classic experimental demonstration in 1974, which makes this a natural first stop.

People judge how common or likely something is by how easily examples come to mind. Tversky and Kahneman introduced it in 1973, and it explains why vivid or recent events feel more frequent than they are.

Here the estimate goes wrong because general statistics are ignored in favor of a vivid case. The page uses the disease-screening problem, where a positive test feels decisive although the condition is rare, and ties the finding to Kahneman and Tversky and the representativeness heuristic.

The belief that a streak must balance out, though the events are independent. The page recalls the Monte Carlo casino in 1913, where the ball landed on black twenty six times in a row, and notes Laplace described the pattern in 1796.

Once an estimate or belief is formed, people search for, interpret and recall information in ways that support it. Peter Wason experiments on hypothesis testing gave the bias its modern experimental grounding.

A bias in which evidence is collected only from what passed a selection process. The page recounts Abraham Wald, in World War Two, assessing aircraft vulnerability from the damage on planes that returned.

After an outcome is known, people overestimate how predictable it was and misremember their own prior uncertainty. Baruch Fischhoff described it formally in 1975, after hearing Paul Meehl say that clinicians overestimate their ability to have foreseen a case outcome.

Money already spent and unrecoverable should not matter to a future decision, yet people let it shape their choices. The page calls this throwing good money after bad and cites a study of 141 horse bettors from 1968.

Losses weigh more heavily than equal gains. Kahneman and Tversky coined the term in 1979 within prospect theory, and their experiments suggested losses are felt roughly twice as strongly, which helps explain why people resist cutting their losses.

The same lack of skill that produces poor performance also hides it, so people with low ability overestimate their competence. Dunning and Kruger described it in 1999, and it is usually measured by comparing self-assessment with objective performance.

Successes are credited to ability or effort and failures to outside circumstances, in a way that protects self-esteem. Its roots lie in Fritz Heider attribution work, and Miller and Ross reviewed it in 1975.

The path ends with explanations of other people. Observers overweight personality and underweight situation, a pattern Lee Ross named in 1977 after the 1967 Jones and Harris experiment, and one people apply less readily to themselves, as the previous stop showed.