Thinking and Deciding

382 QUANTITATIVE JUDGMENT
search your memory for attractive aspects of each city: You might think about the
Louvre in Paris, or St. Peter’s in Rome, or the fact that you do not speak Italian. 8
Whatever attribute you find, you eliminate all of the options in the choice set that
lack this single attribute. If you think of the Louvre first, you eliminate Rome, and
the decision is made. You might, of course, think of some aspect of these cities that
does not distinguish them for you, such as “good food.” In this case, you simply
continue the search for aspects. When there are more than two options, you may
find an aspect that allows you to eliminate one of them but leaves others for you
to consider. Tversky also assumes that you tend to think of the more important
aspects first, but the order of thinking of aspects is not fixed. Because the order is
not fixed, the choice you would make is somewhat unpredictable, especially when
two options each have many different but attractive aspects. This sort of thinking
has been found in think-aloud protocols of decision making on such decisions as
choosing an apartment (Payne, Braunstein, and Carroll, 1978; Svenson, 1979).
In the Rome-Paris example, we can think of many different attributes that distinguish
Rome and Paris. Your chance of finding one of these before hitting on the
bottle of wine as the decisive attribute is quite high — so high that the wine is unlikely
to affect your choice. (For it to do so, you would have to hit on it before any
other distinguishing attributes.) When the choice is between Rome with wine and
Rome without, however, there are no other distinguishing attributes. You would go
through all the attributes and find them identical for the two choices before you hit
on the wine, so you would choose the trip with wine with probability 1.
In the record example, many people are likely to think of attributes that make
us favor Debussy or Beethoven in general. If we think of an attribute that favors
Beethoven, this will probably eliminate the Debussy. If there are two Beethoven
records to choose from, however, we will then have to continue the search for more
attributes to distinguish them. We are unlikely to discover an attribute that allows us
to eliminate one of the Beethoven records and the Debussy all at once. This is why
we appear to make the decision in two steps, first between Beethoven and Debussy,
then, if we decide on Beethoven, between the two Beethoven recordings.
Tversky (1972) points out that this heuristic is encouraged by advertisers who try
to induce people to focus on certain attributes of the products they are promoting.
Here is another example from a television commercial for a computer-programming
school:
‘There are more than two dozen companies in the San Francisco area
which offer training in computer programming.’ The announcer puts
some two dozen eggs and one walnut on the table to represent the alternatives,
and continues: ‘Let us examine the facts. How many of these
schools have on-line computer facilities for training?’ The announcer
removes several eggs. ‘How many of these schools have placement services
that would help you find a job?’ The announcer removes some
8 In this analysis, an “attractive aspect” could be identical to the absence of an unattractive aspect.