Anyone who has tried to break a
bad habit has experienced the trouble with willpower. You want to stick to your diet, but you find
yourself standing at a buffet filled with tempting desserts. You want to avoid the desserts, but before
you know it, there is a beautiful piece of cake on your plate. And at least for that night, the diet is
blown.
Psychologists have been quite
interested in understanding why willpower works so poorly. Essentially, your action system has two
components: a Go System and a Stop System. The Go System is the one that supports
action. It helps you engage in lots of
activities that allow you to achieve your goals. It also supports the many habits that allow
you to get through your day effectively without having to think about the many
actions you take on a daily basis.
The Stop System (what we call
willpower) applies the brakes to actions that are begun by the Go System, but
conflict with some other newer goal.
Dieting is a great example. You
have built up lots of eating habits over the years. When you decide to go on a diet, you are
adding a new goal that conflicts with many of those eating habits. You need your Stop System to prevent you from
eating foots that would get in the way of your diet.
Unfortunately, the Stop System is
not as efficient as the Go System. Lots
of things can interfere with it. When
you are stressed, the Stop System does not work so well. Drugs and alcohol can prevent the Stop System
from working. In addition, lots of
research on ego depletion suggests
that when you use the Stop System a lot, it begins to work less
effectively. So, a long day of having to
control yourself at work can get in the way of your diet is likely to be in
peril.
There is an ongoing debate in the
research community about why these ego depletion effects happen. An intriguing set of studies by Matthew
Gailliot and Roy Baumeister in a 2007 issue of Personality and Social Psychology Review suggested that ego
depletion may reflect actual energy levels within your body. There were two kinds of data that led them to
this conclusion. First, they found that
having to use the Stop System repeatedly led to decreases in blood glucose
(sugar) levels (as measured with the kinds of glucometers that diabetics use
regularly). Second, they found that
after making people use their Stop System, a high-glucose drink kicked the Stop
System back into gear.
A number of other researchers
questioned these findings, however. A
new set of studies by Daniel Molden, Chin Ming-Hui, Abigail Scholer, Brian
Meier, Eric Noreen, Paul D’Agostino, and Valerie Martin in the October, 2012
issue of Psychological Science
strongly suggests that failures of willpower reflect aspects of the
motivational system, and not low levels of energy.
First, they repeated the
physiological studies of blood glucose levels with more sensitive measuring
equipment. They taxed the Stop System
using a task that has been used in previous studies. They asked participants to look at a passage
of text and cross out every letter e.
This is not hard to do. Some
participants then did the same task with a second passage. Another group had to cross out every e that
was not next to another vowel. This
latter task is harder and requires a lot of use of the Stop System. They measured people’s blood glucose before
and after doing this task. Finally, they
gave people a seven-letter word and asked them to generate as many smaller words
as they could from the letters.
Consistent with lots of previous
work, people who just did the more difficult letter-crossing task spent less
time generating words than people who did the easier task. That is the typical ego depletion
effect. However, the measure of blood
glucose levels showed no difference between the groups in their glucose
levels. That is, the more difficult
self-control task did not consume more glucose than the easier task.
Next, the researchers explored the
effect of drinking a high-sugar drink.
They pointed out that drinking a sugary drink could have many effects on
a person. Obviously, one is that it
raises the level of glucose in the blood.
However, the taste of the glucose is pleasant, and that might make
people happy. Most importantly, the
presence of glucose in the mouth might activate reward centers in the brain
that could influence people’s motivation to perform a task.
They explored this possibility in
several other studies. In one study,
they had people do the same letter-crossing task I just described. Then, people swished a sweet drink in their
mouth and spit it out. For some people,
that sweet drink had an artificial sweetener in it (which does not activate
reward centers in the brain), while for others the drink had glucose in it. After that, people were asked to squeeze a
hand grip for as long as they could. Squeezing
a hand grip has been used as a measure of persistence in other studies.
The group that swished the drink
with artificial sweetener showed the usual ego depletion effect. Those who did the hard letter-crossing task
held the grip for less time than those who did the easy letter-crossing
task. The group that swished the glucose
drink in their mouth showed no ego-depletion effect. They were able to hold the hand grip for
about the same amount of time regardless of which letter-crossing task they
did. The researchers did a few other
studies showing similar effects of glucose on more cognitive tasks.
So, what does all this mean?
Failures of willpower reflect the
operation of the motivational system and not just a lack of energy. How will this help you engage your Stop
System? If you find yourself in a
difficult spot, try to find a way to give yourself a little reward. When you stand in front of that buffet table
filled with desserts, seek out a friend and have a fun conversation. That rewarding conversation will help revive
the Stop System and keep you on your diet.
This set of studies also shows how
the scientific process works. The
initial studies had some intriguing results.
Whenever scientists find something new, others come along to explore the
topic more fully. Even though the
initial explanation (that the Stop System requires energy) does not seem to be
right, we have learned a lot about motivation from this initial set of studies.
