DECISION-MAKING THEORY AND RESEARCHestimations on an unfamiliar task were affected by
the quantity of the task work completed. Partici-
pants whose work resulted in a large pile of materi-
al rated their performance higher than partici-
pants whose work resulted in small pile. However,
the amount of actual work done was the same.
Moreover, if the pile was not in sight at the time of
judgment, then performance estimates did not differ.
Pelham, Sumarta, and Myaskovsky (1994) dem-
onstrated an effect similar to the quantity princi-
ple, which they called the numerosity heuristic. This
heuristic refers to the use of the number of units as
a cue for judgment. For example, the researchers
found that participants rated the area of a circle as
larger when the circle was presented as pieces that
were difficult to imagine as a whole circle than if
the pieces were presented so that it was easy to
imagine, and larger than the undivided circle. This
result suggests that dividing a whole into pieces
will lead to those pieces being thought of as larger
than the whole, and this will be especially so when
it is hard to imagine the pieces as the whole. That
is, the numerosity of the stimulus to be rated can
affect the rating of that stimulus.
Anchoring. Anchoring is similar to availability
and quantity heuristics, because it involves making
a judgment using some stimulus as a starting point,
and adjusting from that point. For example, Sherif,
Taub, and Hovland (1958) had people make esti-
mates of weight on a six-point scale. Prior to each
estimation, subjects held an ‘‘anchor’’ weight that
was said to represent ‘‘6’’ on the scale. When the
anchor’s weight was close to the other weights,
then subjects’ judgments were also quite close to
the anchor, with a modal response of 6 on the six-
point scale. However, heavier anchors resulted in
lower responses. The heaviest anchor produced a
modal response of 2.
However, anchoring need not involve the di-
rect experience of a stimulus. Simply mentioning a
stimulus can lead to an anchoring effect. Kahneman
and Tversky (1972) assigned people the number
10 or 65 by means of a seemingly random process
(a wheel of fortune). These people then estimated
the percentage of African countries in the United
Nations. Those assigned the number 10 estimated
25 percent, and those assigned the number 65
estimated 45 percent (at the time the actual per-
centage was 35). This indicates the psychological
impact of one’s starting point (or anchor), when
making a judgment.
An anecdotal example of someone trying to
fight the anchoring phenomenon is a writer who
tears up a draft of what she is working on, and
throws it away, rather than trying to work with that
draft. It may seem wasteful to have created some-
thing, only to throw it out. However, at times,
writers may feel that what they have produced is
holding them in a place that they do not want to
be. Thus, it could be better to throw out that draft,
rather than trying to rework it, which is akin to
pulling up anchor.
Endowment Effect. Related to anchoring is
the tendency people have to stay where they are.
This tendency is known as the endowment effect
(Thaler 1980) or the status quo bias (Samuelson and
Zeckhauser 1988). This tendency results in people
wanting more for something they already have
than they would be willing to pay to acquire that
same thing. In economic terms, this would be
described as a discrepancy between what people
are willing to pay (WTP) and what they are willing
to accept (WTA). Kahneman, Knetsch, and Thaler
(1990) found WTA amounts much higher for an
item already possessed than WTP amounts to
obtain that item. In their study, half of the people
in a university class were given a university coffee
mug, and half were not. A short time later, the
people with the mugs were asked how much mon-
ey they wanted for their mug (their WTA amount),
and those without the mug were asked how much
they would pay to get a mug (their WTP amount).
The median WTA amount was about twice the
median WTP amount: WTA = $7.12, WTP = $2.87.
Thus, few trades were made, and this is consistent
with the idea that people often seem to prefer what
they have to what they could have.
Representativeness. People may make judg-
ments using representativeness, which is the tenden-
cy to judge events as more likely if they represent
the typical or expected features for that class of
events. Thus, representativeness occurs when peo-
ple judge an event using an impression of the
event rather than a systematic analysis of it. Two
examples of representativeness misleading people
are the gambler’s fallacy and the conjunction fallacy.
The gambler’s fallacy is the confusion of inde-
pendent and dependent events. Independent events
are not causally related to each other (e.g., coin