Kahneman, Mental Effort, and the Scary Parole Study
By Bryan Caplan
Critics of The Myth of the Rational Voter often attack it as psychologically implausible. (See especially Bennett and Friedman’s critique in Critical Review). If, as I maintain, rationality responds to incentives, doesn’t this mean that people make conscious decisions to believe claims they know to be false?
As you’d expect, I disagree. Only after reading Daniel Kahneman’s Thinking, Fast and Slow, though, did I discover how strongly empirical psychology backs me up. Kahneman’s book revolves around his distinction between knee-jerk “System 1” thinking and logical “System 2” thinking. When the costs of cognition rise, we use System 2 less, giving impulsive System 1 freer reign. Kahneman:
It is now a well-established proposition that both self-control and
cognitive effort are forms of mental work. Several psychological
studies have shown that people who are simultaneously challenged by a
demanding cognitive task and by a temptation are more likely to yield
to the temptation. Imagine that you are asked to retain a list of seven
digits for a minute or two. You are told that remembering the digits is
your top priority. While your attention is focused on the digits, you
are offered a choice between two desserts: a sinful chocolate cake and
a virtuous fruit salad. The evidence suggests that you would be more
likely to select the tempting chocolate cake when your mind is loaded
with digits. System 1 has more influence on behavior when System 2 is
busy, and it has a sweet tooth.
A slice of the evidence:
Baumeister’s group has repeatedly found that an effort of will or self-control is tiring; if you have had to force yourself to do something, you are less willing or less able to exert self-control when the next challenge comes around. The phenomenon has been named ego depletion. In a typical demonstration, participants who are instructed to stifle their emotional reaction to an emotionally charged film will later perform poorly on a test of physical stamina–how long they can maintain a strong grip on a dynamometer in spite of increasing discomfort. The emotional effort in the first phase of the experiment reduces the ability to withstand the pain of sustained muscle contraction, and ego-depleted people therefore succumb more quickly to the urge to quit.
How general is this “depletion effect”? Very:
The list of situations and tasks that are now known to deplete self-control is long and varied. All involve conflict and the need to suppress a natural tendency. They include:
avoiding the thought of white bears
inhibiting the emotional response to a stirring film
making a series of choices that involve conflict
trying to impress others
responding kindly to a partner’s bad behavior
interacting with a person of a different race (for prejudiced individuals)
The list of indications of depletion is also highly diverse:
deviating from one’s diet
overspending on impulsive purchases
reacting aggressively to provocation
persisting less time in a handgrip task
performing poorly in cognitive tasks and logical decision making
Kahneman illustrates this generality with the scariest experiment in the book:
A disturbing demonstration of depletion effects in judgment was recently reported in the Proceedings of the National Academy of Sciences. The unwitting participants in the study were eight parole judges in Israel. They spend entire days reviewing applications for parole. The cases are presented in random order, and the judges spend little time on each one, an average of 6 minutes. (The default decision is denial of parole; only 35% of requests are approved. The exact time of each decision is recorded, and the times of the judges’ three food breaks–morning break, lunch, and afternoon break–during the day are recorded as well.) The authors of the study plotted the proportion of approved requests against the time since the last food break. The proportion spikes after each meal, when about 65% of requests are granted. During the two hours or so until the judges’ next feeding, the approval rate drops steadily, to about zero just before the meal. As you might expect, this is an unwelcome result and the authors carefully checked many alternative explanations.
If I were Jeff Friedman, I might insist that this experiment can’t be right. “Are we supposed to believe that judges explicitly think, ‘Since I’m tired and hungry, I now choose to believe that criminals are less deserving of parole?'” But the experiment requires nothing of the kind. We don’t need to assume that judges are self-conscious arbitrary tyrants. We merely need to assume that (a) denial of parole is the default, (b) going against your default position requires intellectual effort, and (c) intellectual effort depends on your circumstances – including the consequences of being wrong.
Similarly, for The Myth of the Rational Voter to be right, I don’t have to assume that protectionists explicitly think, “Since I hate foreigners, I now choose to believe that trade barriers make us richer.” I merely need to assume that (a) most people’s default is to blame economic problems on foreigners and other disliked scapegoats, (b) going against this default position requires intellectual effort, and (c) intellectual effort depends on your circumstances – including the consequences of being wrong about the economic effects of foreigners.
The last step is simply to point out that the individual voter has almost no effect on policy, so the consequence of being wrong about trade policy is roughly zero. The result: Politicians who want to win pander to the vast majority of voters who never took the effort to second-guess their emotionally satisfying protectionist default.