Daniel Kahneman received the Nobel Prize in economics sciences in 2002, December 8, Stockholm, Sweden. This article is the edited version of his Nobel Prize lecture. The author comes back to the problems he has studied with the late Amos Tversky and to debates conducting for several decades already. The statement is based on worked out together with Shane Federik the quirkiness of human judgment. Language: ru

My first exposure to the psychological assumptions of economics was in a report that Bruno Frey wrote on that subject in the early 1970's. Its first or second sentence stated that the agent of economic theory is rational and selfish, and that his tastes do not change. I found this list quite startling, because I had been professionally trained as a psychologist not to believe a word of it. The gap between the assumptions of our disciplines appeared very large indeed. Has the gap been narrowed in the intervening 30 years? A search through some introductory textbooks in economics indicates that if there has been any change, it has not yet filtered down to that level: the same assumptions are still in place as the cornerstones of economic analysis. However, a behavioral approach to economics has emerged in which the assumptions are not held sacrosanct. In the following I comment selectively on the developments with regard to the three assumptions, on both sides of the disciplinary divide.

This paper presents a critique of expected utility theory as a descriptive model of decision making under risk, and develops an alternative model, called prospect theory. Choices among risky prospects exhibit several pervasive effects that are inconsistent with the basic tenets of utility theory. In particular, people underweight outcomes that are merely probable in comparison with outcomes that are obtained with certainty. This tendency, called the certainty effect, contributes to risk aversion in choices involving sure gains and to risk seeking in choices involving sure losses. In addition, people generally discard components that are shared by all prospects under consideration. This tendency, called the isolation effect, leads to inconsistent preferences when the same choice is presented in different forms. An alternative theory of choice is developed, in which value is assigned to gains and losses rather than to final assets and in which probabilities are replaced by decision weights. The value function is normally concave for gains, commonly convex for losses, and is generally steeper for losses than for gains. Decision weights are generally lower than the corresponding probabilities, except in the range of low prob-abilities. Overweighting of low probabilities may contribute to the attractiveness of both insurance and gambling. 1.

Observed preference reversal (PR) cannot be adequately explained by violations of independence, the reduction axiom, or transitivity. The primary cause of PR is the failure of procedure invariance, especially the overpricing of low-probability high-payoff bets. This result violates regret theory and generalized (nonindependent) utility models. PR and a new reversal involving time preferences are explained by scale compatibility, which implies that payoffs are weighted more heavily in pricing than in choice.

Community standards of fairness for the setting of prices and wages were elicited by telephone surveys. In customer or labor markets, it is acceptable for a firm to raise prices (or cut wages) when profits are threatened and to maintain prices when costs diminish. It is unfair to exploit shifts in demand by raising prices or cutting wages. Several market anomalies are explained by assuming that these standards of fairness influence the behavior of firms.

Contrary to theoretical expectations, measures of willingness to accept greatly exceed measures of willingness to pay. This paper reports several experiments that demonstrate that this "endowment effect" persists even in market settings with opportunities to learn. Consumption objects (e.g., coffee mugs) are randomly given to half the subjects in an experiment. Markets for the mugs are then conducted. The Coase theorem predicts that about half the mugs will trade, but observed volume is always significantly less. When markets for "induced-value" tokens are conducted, the predicted volume is observed, suggesting that transactions costs cannot explain the undertrading for consumption goods.

Contrary to theoretical expectations, measures of willingness-to-accept greatly exceed measures of willingness-to-pay. This paper reports several experiments that demonstrate that this "endowment effect" persists even in market settings with opportunities to learn. Consumption objects (e.g., coffee mugs) are randomly given to half the subjects in an experiment. Markets for the mugs are then conducted. The Coase theorem predicts that about half the mugs will trade, but observed volume is always significantly less. When markets for "induced-value" tokens are conducted, the predicted volume is observed, suggesting that transactions costs cannot explain the undertrading for consumption goods.

Toward National Well-Being Accounts by Daniel Kahneman, Alan B. Krueger, David Schkade, Norbert Schwarz and Arthur Stone. Published in volume 94, issue 2, pages 429-434 of American Economic Review, May 2004