Daniel Kahneman Nobel Lecture

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MAPS OF BOUNDED RATIONALITY: 

A PERSPECTIVE ON INTUITIVE JUDGMENT 

AND CHOICE

Prize Lecture, December 8, 2002

by

D

ANIEL

K

AHNEMAN

*

Princeton University, Department of Psychology, Princeton, NJ 08544, USA.

The work cited by the Nobel committee was done jointly with the late Amos

Tversky (1937–1996) during a long and unusually close collaboration.

Together, we explored the psychology of intuitive beliefs and choices and ex-

amined their bounded rationality. This essay presents a current perspective

on the three major topics of our joint work: heuristics of judgment, risky

choice, and framing effects. In all three domains we studied intuitions –

thoughts and preferences that come to mind quickly and without much re-

flection. I review the older research and some recent developments in light of

two ideas that have become central to social-cognitive psychology in the in-

tervening decades: the notion that thoughts differ in a dimension of accessi-

bility – some come to mind much more easily than others – and the distinc-

tion between intuitive and deliberate thought processes.

Section 1 distinguishes two generic modes of cognitive function: an intui-

tive mode in which judgments and decisions are made automatically and

rapidly, and a controlled mode, which is deliberate and slower. Section 2 de-

scribes the factors that determine the relative accessibility of different judg-

ments and responses. Section 3 explains framing effects in terms of differen-

tial salience and accessibility. Section 4 relates prospect theory to the general

*

This essay revisits problems that Amos Tversky and I studied together many years ago, and con-

tinued to discuss in a conversation that spanned several decades. The article is based on the

Nobel lecture, which my daughter Lenore Shoham helped put together. It builds on an analysis

of judgment heuristics that was developed in collaboration with Shane Frederick (Kahneman

and Frederick, 2002). Shane Frederick, David Krantz, and Daniel Reisberg went well beyond the

call of friendly duty in helping with this effort. Craig Fox, Peter McGraw, Daniel Read, David

Schkade and Richard Thaler offered many insightful comments and suggestions. Kurt Schoppe

provided valuable assistance, and Geoffrey Goodwin and Amir Goren helped with scholarly fact-

checking. My research is supported by NSF 285-6086 and by the Woodrow Wilson School for

Public and International Affairs at Princeton University. A different version of this article is to ap-

pear in the American Economic Review (December 2003).

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proposition that changes and differences are more accessible than absolute

values. Section 5 reviews an attribute substitution model of heuristic judg-

ment. Section 6 describes a particular family of heuristics, called prototype

heuristics. Section 7 concludes with a review of the argument.

1. INTUITION AND ACCESSIBILITY

From its earliest days, the research that Tversky and I conducted was guided

by the idea that intuitive judgments occupy a position – perhaps correspond-

ing to evolutionary history – between the automatic operations of perception

and the deliberate operations of reasoning. Our first joint article examined

systematic errors in the casual statistical judgments of statistically sophisticat-

ed researchers (Tversky & Kahneman, 1971). Remarkably, the intuitive judg-

ments of these experts did not conform to statistical principles with which

they were thoroughly familiar. In particular, their intuitive statistical infer-

ences and their estimates of statistical power showed a striking lack of sensi-

tivity to the effects of sample size. We were impressed by the persistence of dis-

crepancies between statistical intuition and statistical knowledge, which we

observed both in ourselves and in our colleagues. We were also impressed by

the fact that significant research decisions, such as the choice of sample size

for an experiment, are routinely guided by the flawed intuitions of people

who know better. In the terminology that became accepted much later, we

held a two-system view, which distinguished intuition from reasoning. Our re-

search focused on errors of intuition, which we studied both for their intrin-

sic interest and for their value as diagnostic indicators of cognitive mecha-

nisms.

The two-system view

The distinction between intuition and reasoning has been a topic of consid-

erable interest in the intervening decades (among many others, see Epstein,

1994; Hammond, 1996; Jacoby, 1981, 1996; and numerous models collected

by Chaiken & Trope, 1999; for comprehensive reviews of intuition, see

Hogarth, 2002; Myers, 2002). In particular, the differences between the two

modes of thought have been invoked in attempts to organize seemingly con-

tradictory results in studies of judgment under uncertainty (Kahneman &

Frederick, 2002; Sloman, 1996, 2002; Stanovich, 1999; Stanovich & West,

2002). There is considerable agreement on the characteristics that distin-

guish the two types of cognitive processes, which Stanovich and West (2000)

labeled System 1 and System 2. The scheme shown in Figure 1 summarizes

these characteristics: The operations of System 1 are fast, automatic, effort-

less, associative, and difficult to control or modify. The operations of System

2 are slower, serial, effortful, and deliberately controlled; they are also rela-

tively flexible and potentially rule-governed. As indicated in Figure 1, the op-

erating characteristics of System 1 are similar to the features of perceptual

processes. On the other hand, as Figure 1 also shows, the operations of

System 1, like those of System 2, are not restricted to the processing of cur-

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