ry of choice that completely ignores feelings such as
the pain of losses and the
regret of mistakes is not only descriptively unrealistic. It also leads to pre-
scriptions that do not maximize the utility of outcomes as they are actually ex-
perienced – that is, utility as Bentham conceived it (Kahneman, 1994, 2000c;
Kahneman, Wakker, & Sarin, 1997).
4. ATTRIBUTE SUBSTITUTION: A MODEL OF JUDGMENT
BY HEURISTIC
The first joint research program that Tversky and I undertook was a study of
various types of judgment about uncertain events, including numerical pre-
dictions and assessments of the probabilities of hypotheses. We reviewed this
work in an integrative article (Tversky & Kahneman, 1974), which aimed to
show “that people rely on a limited number of heuristic principles which re-
duce the complex tasks of assessing probabilities and predicting values to sim-
pler judgmental operations. In general, these heuristics are quite useful, but
sometimes they lead to severe and systematic errors.” (p. 1124). The second
paragraph of that article introduced the idea that “the subjective assessment
of probability resembles the subjective assessments of physical quantities such
as distance or size. These judgments are all based on data of limited validity,
which are processed according to heuristic rules.” The concept of heuristic was
illustrated by the role of the blur of contours as a potent determinant of the
perceived distance of mountains. The observation that reliance on blur as a
distance cue will cause distances to be overestimated on foggy days and un-
derestimated on clear days was the example of a heuristic-induced bias. As this
example illustrates, heuristics of judgment were to be identified by the char-
acteristic errors that they inevitably cause.
Three heuristics of judgment, labeled representativeness, availability and
anchoring, were described in the 1974 review, along with a dozen systematic
biases, including non-regressive prediction, neglect of base-rate information,
overconfidence and overestimates of the frequency of events that are easy to
recall. Some of the biases were identified by systematic errors in estimates of
known quantities and statistical facts. Other biases were identified by system-
atic discrepancies between the regularities of intuitive judgments and the
principles of probability theory, Bayesian inference or regression analysis.
The article defined the so-called “heuristics and biases approach” to the study
of intuitive judgment, which has been the topic of a substantial research lit-
erature (Kahneman, Slovic, & Tversky, 1982; Gilovich, Griffin, & Kahneman,
2002) and has also been the focus of substantial controversy.
Shane Frederick and I recently revisited the conception of heuristics and
biases, in the light of developments in the study of judgment and in the
broader field of cognitive psychology in the intervening three decades
(Kahneman & Frederick, 2002). The new model departs from the original
formulation of heuristics in three significant ways: (i) it proposes a common
process of attribute substitution to explain how judgment heuristics work; (ii)
it extends the concept of heuristic beyond the domain of judgments about
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466
uncertain events; (iii) it includes an explicit treatment of the conditions un-
der which intuitive judgments will be modified or overridden by the moni-
toring operations associated with System 2.
Attribute substitution
The 1974 article did not include a definition of judgmental heuristics.
Heuristics were described at various times as principles, as processes, or as
sources of cues for judgment. The vagueness did no damage, because the re-
search program focused on a total of three heuristics of judgment under un-
certainty, which were separately defined in adequate detail. In contrast,
Kahneman and Frederick (2002) offered an explicit definition of a generic
heuristic process of attribute substitution: A judgment is said to be mediated by
a heuristic when the individual assesses a specified target attribute of a judg-
ment object by substituting a related heuristic attribute that comes more readi-
ly to mind. This definition elaborates a theme of the early research, that people
who are confronted with a difficult question sometimes answer an easier
one instead. Thus, a person who is asked “What proportion of long-distance
relationships break up within a year?” may answer as if she had been asked
“Do instances of swift breakups of long-distance relationships come readily to
mind?” This would be an application of the availability heuristic. A respon-
dent asked to assess the probability that team A will beat team B in a basket-
ball tournament may answer by mapping an impression of the relative
strength of the two teams onto the probability scale (Tversky & Koehler,
1994). This could be called a “relative strength heuristic”. In both cases, the
target attribute is low in accessibility and another attribute, which is (i) relat-
ed to the target, and (ii) highly accessible, is substituted in its place.
The word ‘heuristic’ is used in two senses in the new definition. The noun
refers to the cognitive process, and the adjective in ‘heuristic attribute’ speci-
fies the substitution that occurs in a particular judgment. For example, the
representativeness heuristic is defined by the use of representativeness as a
heuristic attribute to judge probability. The definition excludes anchoring ef-
fects, in which judgment is influenced by temporarily raising the accessibility
Figure 7.