How did Amos Tversky and Daniel Kahneman study mistakes in human reasoning?

Psychologists Amos Tversky and Daniel Kahneman studied human reasoning by investigating how individuals make decisions under uncertainty. They demonstrated that people often rely on heuristics—mental shortcuts that simplify complex problems but can lead to systematic cognitive biases.1

Their research identified three primary heuristics:
* Representativeness: Judging probability based on how closely an event or object resembles a stereotype, often ignoring objective factors like base rates.1
* Availability: Assessing frequency or probability based on the ease with which examples come to mind, which is often influenced by salience or recency.1
* Anchoring and adjustment: Making estimates by starting from an initial value (the anchor) and adjusting insufficiently, leading to biased final results.1

In the context of logic, Tversky and Kahneman identified specific cognitive mistakes, such as the conjunctive fallacy, where people incorrectly perceive added information as increasing the probability of a statement. They also highlighted how reasoners often fail to account for base-rate probabilities, such as in the "juror's fallacy." Their work challenged the traditional model of rational choice, suggesting that human reasoning is inherently prone to these predictable errors.21