382 • CHAPTER 13 Reasoning and Decision Making
The results for the two groups are shown in the columns headed “Passed” and
“Failed” in Table 13.5. Notice that there is no difference between the two groups. Fifty-
four percent of the participants in the “pass” group and 57 percent of those in the “fail”
group opted to buy the vacation package.
The interesting result happened when a third group was given the same situation,
except these participants were told that the outcome of the exam wouldn’t be available
for 2 more days. Only 32 percent of these participants opted for the package, and 61
percent decided they would pay the $5 so they could put off making the decision until
they knew whether or not they had passed the exam. Thus, 61 percent of the partici-
pants in this group did not want to make a decision about the trip until they found out
whether they had passed or failed, even though the results for the other two groups
indicate that passing or failing made no difference in the actual decision about the
vacation packages.
To explain this result, Tversky and Shafi r suggest that once students know the out-
come, they can then assign a reason for deciding to buy the vacation. Participants who
passed could see the vacation as a reward; participants who failed could see the vacation
as a consolation that would give them time to recuperate before taking the exam again.
Although there are other possible interpretations for these results, there is a great
deal of other evidence that the decision-making process often includes looking for jus-
tifi cation so the person can state a rationale for his or her decision. This is why doctors
may carry out medical tests that might not lead to a different treatment but that provide
additional evidence for the treatment they have recommended, thereby making it easier
to justify the treatment to themselves, their patients, and, if necessary, to the courts
(Tversky & Shafi r, 1992).The Physiology of Thinking
In this section we will consider the types of thinking we have discussed in this chapter and
the previous one. We begin by asking the question, “How is the brain involved in problem
solving, reasoning, and making decisions?” Because all of these forms
of thinking involve a number of different cognitive capacities—
including perception, memory, and the ability to focus and maintain
attention—it isn’t surprising that a number of different areas of the
brain are involved. However, we will focus on one area in particu-
lar, the prefrontal cortex (PFC).EFFECT OF DAMAGE
TO THE PREFRONTAL CORTEX
The prefrontal cortex (● Figure 13.13) is activated by stimuli from
all of the senses, by the retrieval of memories, and by the anticipa-
tion of future events, and can be affected by a person’s emotional
state (Wallis et al., 2001). It is not surprising, therefore, that the
PFC plays a central role in determining complex behaviors thatTABLE 13.5 Choice Behavior and Knowledge of Exam OutcomePassed Failed Result in 2 DaysBuy vacation package 54 % 57 % 32 %
Don’t buy 16 12 7
$5 to keep open option to buy later 30 31 61Frontal lobePrefrontal cortex●FIGURE 13.13 Brain showing location of the prefrontal
cortex (PFC).Copyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.