THE MOLECULE OF MOREthe participant began to eat, the scientist left the room, reminding the
participant that she must only eat the food she was assigned to.
None of the participants assigned to the radishes broke the rules and
ate a cookie, but they were obviously tempted. The researchers peeked
around a curtain to watch what they did. “Several of them [looked]
longingly at the chocolate display and in a few cases even pick[ed] up
the cookies to sniff at them.”
After about 5 minutes, the scientist returned, and told the partic-
ipant that the next step in the study was something completely unre-
lated: it was a test of problem-solving ability. What the participants
weren’t told was that the problem couldn’t be solved. The question was,
how long would each participant persevere at this impossible task?
The participants who had been allowed to eat cookies worked
on the problem for about 19 minutes. The ones who had been only
allowed to eat radishes, those who had to exert self-control to counter-
act their desire for cookies, persisted at the task for only 8 minutes—less
than half the time—before they gave up. The researchers concluded,
“Resisting temptation seems to have produced a psychic cost, in the
sense that afterward participants were more inclined to give up easily
in the face of frustration.” If you’re on a diet, the more times you resist
temptation, the more likely you are to fail the next time around. Will-
power is a limited resource.
THE WILLPOWER EXERCISE MACHINEIf willpower is like a muscle, can it be strengthened through exercise?
Yes, but it requires some high tech “exercise equipment,” the kind of
equipment that scientists at the Center for Cognitive Neuroscience at
Duke University used to see if they could enhance the part of the brain
people use for willpower.
First they made things easy. They paid participants money if they
completed a task successfully. It’s easy to get motivated when there is an
immediate reward. Using a brain scanner, they were able to see activa-
tion of the ventral tegmental area of the brain, the place where both