Daniel Kahneman and Amos Tversky: Thinking About Thinking

How two psychologists transformed economics by showing systematic patterns in how people misjudge risk and value, including prospect theory.

Daniel Kahneman and Amos Tversky were Israeli psychologists who began working together in the late 1960s. Their research on how people make judgements and decisions reshaped economics, even though neither was trained as an economist. Kahneman received the Nobel prize in economics in 2002. Tversky had died in 1996, and the prize is not awarded after death, but Kahneman made clear the work was joint.

Heuristics and biases

Kahneman and Tversky showed that people often use mental shortcuts, called heuristics, to make judgements quickly. These shortcuts usually work but lead to predictable errors. For example:

Availability: people judge how likely something is by how easily examples come to mind, so vivid events like plane crashes seem more common than they are.
Anchoring: people’s estimates are pulled toward an initial number, even an irrelevant one.
Representativeness: people judge probability by how closely something matches a stereotype, ignoring basic statistics.

Prospect theory

In 1979 they published prospect theory, a description of how people actually make choices involving risk. Key features include:

People judge outcomes as gains or losses relative to a reference point, not as final levels of wealth.
Loss aversion: losses hurt more than equal gains feel good, often estimated at roughly twice as much.
People tend to be risk averse for gains but willing to gamble to avoid losses.
People overweight small probabilities, which helps explain both lottery tickets and insurance.

The same choice, framed differently

In one famous experiment, people were asked to choose between programmes to fight a disease expected to kill 600 people. When options were described in terms of lives saved, most chose the certain option. When the same options were described in terms of deaths, most chose the risky option. Only the framing changed, yet choices reversed.

Impact on economics

Their work helped create behavioural economics, which combines psychology with economics. It has influenced policy through tools like automatic enrolment in pension plans. Kahneman’s 2011 book Thinking, Fast and Slow brought these ideas to millions of readers. Kahneman died in 2024.

Thinking the research shows people are irrational in every way

Kahneman and Tversky showed that errors are systematic and predictable, not random. That predictability is what makes their findings useful: if we know how people tend to misjudge, we can design choices and policies that help them decide better.

Key takeaways

Kahneman and Tversky showed that mental shortcuts lead to predictable errors.
Availability, anchoring and representativeness are key heuristics.
Prospect theory describes choices based on gains and losses, with loss aversion.
Their work founded behavioural economics; Kahneman won the Nobel prize in 2002.