Thinking and Deciding

58 THE STUDY OF THINKING
our goals best, usually, if our beliefs are accurate, even if they are unpleasant. (Some
possible exceptions are discussed in the next chapter.) Yet, psychologists have found
for a long time that people often adopt beliefs that are comfortable, beliefs that make
them happy — at least in the short term, before they suffer the consequences of acting
on these beliefs. For example, people are happy thinking of themselves as good
judges and good decision makers. They will thus distort their beliefs about the world
so as to make their past decisions and judgments look good. These distortions often
involve self-manipulation, such as presenting oneself with evidence that favors the
belief one wants to have, and then conveniently forgetting that the evidence was selected
exactly for this purpose and that counter-evidence was intentionally neglected.
Biases in this category have been extensively studied by social psychologists as well
as by researchers in the field of judgments and decisions.
In principle there should be another category of biases here, looking at the effect
of beliefs on goals or desires. Scholars such as Jon Elster (1983) have written about
“adaptive preference formation,” or the sour-grapes effect. We tend to want what
we think we can have, and suppress our desires for what we think is unattainable.
Although these effects are interesting, and this book will have a little to say about
them, they have not been studied much as the effects of goals or desires on beliefs.
Moreover, it isn’t clear what a bias is, because it isn’t clear what the normative model
is.
Section III concerns another part of psychology, psychophysics, the study of
the relation between quantitative attributes and our perception of these attributes. A
standard result of psychophysics is that our sensitivity usually diminishes as intensity
increases. For example, think about judging the distance of a car that is ahead of you
while you are driving. When you are caught in a traffic jam (or tailgating), the
car is very close and a difference of one meter looks like a large difference. When
the car is so far away that you cannot clearly see it, a difference of one meter is not
noticeable at all. The same effect occurs with attributes that are relevant to decisions.
The difference between a prize of $10 and $20 seems subjectively larger than the
difference between $1,010 and $1,020. (If you have $1,000 in your bank account
where you will deposit the prize money, then the latter difference is an accurate
description.) Likewise, the difference between right now and 5 minutes from now
seem larger than that between 24 hours from now and 24 hours plus 5 minutes from
now, in how it might affect a decision about when to get something.
Conclusion
The study of thinking goes back at least to Aristotle and other Greek philosophers,
who attempted to codify the rules of good thinking (in the form of logic), to describe
what goes wrong with our thinking in daily life, and to propose ways of guarding
against the errors we tend to make. In the last century, this speculative approach has
been supplemented with the scientific study of thinking. We no longer have to rely
on our experience alone. We must not, however, let ourselves get carried away with