Kahneman, Tversky and a Nobel for psychology

Behavioral finance has two intellectual parents: psychologists Daniel Kahneman and Amos Tversky. Beginning in the 1970s, they ran experiment after experiment showing that human judgment under uncertainty follows systematic, repeatable errors.

The breakthrough

Their work demonstrated that people do not evaluate risk the way economic theory predicted. We are swayed by how a question is framed, we lean on mental shortcuts (heuristics) that misfire, and we feel losses far more intensely than equivalent gains.

In 2002, Kahneman received the Nobel Memorial Prize in Economic Sciences for integrating psychological research into economics — a remarkable recognition for a psychologist who never took an economics course. (Tversky had died in 1996 and the prize is not awarded posthumously.)

Why it shook finance

The implication was profound: if irrationality is not random noise but a systematic pattern, then it can be studied, predicted, and — crucially — it shows up in market prices. A market made of biased humans will itself be biased in measurable ways.

The takeaway for you

You inherited the same wiring as every test subject in their experiments. Knowing that your errors are not personal failings but built-in features of the human mind is the first step to managing them. The rest of this chapter and the next unpack exactly which shortcuts misfire and how they cost traders money.