Thinking and Deciding

PROMINENCE AND NONCOMPENSATORY STRATEGIES 291
prominence effect. Tversky, Sattath, and Slovic (1988) compared subjects’ choices
in the following problem to other subjects’ responses in a numerical matching task
based on the same problem (p. 373):
About 600 people are killed each year in Israel in traffic accidents. The
ministry of transportation investigates various programs to reduce the
number of casualties. Consider the following two programs, described
in terms of yearly costs (in millions of dollars) and the number of casualties
per year that is expected following the implementation of each
program:
Expected number of casualties Cost (millions)
Program X 500 $55
Program Y 570 $12
When subjects were asked to choose which program they favored, 67% favored Program
X, which saves more lives but at a higher cost per life saved than Program Y.
Subjects in the matching task were given the same situation but with one of the numbers
missing. They were asked to fill in the missing number so that the two programs
would be equally desirable, that is, to match the two programs. From the response to
this question, we can infer what they would have chosen in the choice task (assuming
they would have been consistent). For example, suppose that the cost of Program X
was missing, and a subject wrote down $40 million. We can infer that this subject
would have preferred Program Y: If X and Y are equal when the cost of X is $40
million, then X must be worse than Y when the cost of X is raised. When the relative
desirability of the two programs was inferred in this way from responses on the
matching task, only 4% of the subjects favored Program X; 96% favored Program Y,
the more economical program that saved fewer lives.
Clearly, subjects regard casualties as more important, or more prominent, than
cost. When they choose between the two programs, many subjects base their choice
largely (or entirely) on the single most important attribute: number of casualties. In
the matching task, they are forced to attend to both attributes and to make an explicit
tradeoff between them. The conflict between the two tasks is the prominence effect.
The most plausible explanation of this effect is that in making a choice subjects
often attend only to the most important goal, but in matching they express something
closer to their true tradeoff between the two goals. 1 If this interpretation is correct, it
argues for the use of something like matching, rather than choice, in the measurement
of values. It also suggests that many choices in the real world are inconsistent with
people’s underlying goals.
Compensatory decision strategies are those in which one dimension can compensate
for another. Use of a single dominant dimension is thus a noncompensatory
strategy. Individuals seem to differ in the tendency to use these strategies and in
1 An alternative interpretation is that choice is closer to the true tradeoff and matching leads to excessive
attention to less important goals. We have no reason to think that this is true. We have other evidence,
however, for neglect of less important attributes in choice.