Wason Selection Task CHAPTER 13 REASONING AND DECISION MAKING

What kinds of errors

do people make in

reasoning? (362)

What kinds of

reasoning “traps” do

people get into when

making decisions? (375)

How do emotions

influence decisions by

contestants on shows like

Deal or No Deal? (377)

How does the fact that

people sometimes feel a

need to justify their

decisions affect the process

by which they make those

decisions? (381)

Some Questions We Will Consider

L

ife is full of DECISIONS—making choices between alternatives. What

college to attend? Which movie to see? Which classes to take? Whether to sign

on for more hours at the part-time job with fi nals coming up? Decisions such as

these, both big and small, infl uence daily activities, and sometimes even the trajec-

tory of a person’s life.

But in addition to making decisions, we also engage in the closely related pro-

cess of reasoning. Reasoning has been defi ned as the process of drawing conclu-

sions (Leighton, 2004) and as the cognitive processes by which people start with

information and come to conclusions that go beyond that information (Kurtz

et al., 1999).

We can appreciate the process of reasoning by realizing that decisions are often the

outcome of reasoning. Consider, for example, Raphael’s problem that we described at

the very beginning of the book (see page 4). He had to decide on an alternative form

of transportation for when his car was in the shop. One way to decide between renting

a car, bumming rides from his roommate, and taking the bus is to consider the pros

and cons of each choice. Renting a car provides maximum fl exibility but costs a lot.

Whether or not this alternative makes sense depends on how much money is available

and whether the added convenience is really worth the extra cost. Riding the bus is

cheaper but involves a lot of waiting around outside. The third alternative, bumming

rides from the roommate, seems like a bad choice because Raphael knows that he is

unreliable. By taking these and other factors into account, Raphael reasons his way to

a decision.

As we will see, reasoning is involved in many other situations besides making deci-

sions. For example, we might use reasoning to help solve problems like the ones we

described in Chapter 12. Reasoning is also involved in reading, as we make inferences

about what is happening in a story based on what we know has happened earlier in

the story.

We begin this chapter by focusing on how cognitive psychologists have studied

two specifi c types of reasoning: deductive reasoning and inductive reasoning. We fi rst

consider deductive reasoning, which involves sequences of statements called syllogisms.

For example, if we know that at least a C average is required to graduate from State

U., and that Josie is graduating from State U., we can logically conclude that Josie has

at least a C average.

We then consider inductive reasoning, in which we arrive at conclusions about

what is probably true, based on evidence. Thus, if we know that Richard attended State

U. for 4 years and that he is now the vice president of a bank, we might conclude it is

likely that he graduated. Notice, however, that in this example, we cannot say that he

defi nitely graduated (maybe he never completed all the requirements, and his mother,

who is president of the bank, made him a vice president). Thus, we can make defi nite

conclusions based on deductive reasoning and probable conclusions based on inductive

reasoning. Studying both kinds of reasoning provides insights both about how the mind

works and about everyday thinking.

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