Drug abuse, crime and obesity are but a few of the problems
our nation faces, but they all have one thing in common--people’s
failure to control their behavior in the face of temptation.
While the ability to control and restrain our impulses is
one of the defining features of the human animal, its failure
is one of the central problems of human society. So, why do
we so often lack this crucial ability?
As human beings, we have limited resources to control ourselves,
and all acts of control draw from this same source. Therefore,
when using this resource in one domain, for example, keeping
to a diet, we are more likely to run out of this resource
in a different domain, like studying hard. Once these resources
are exhausted, our ability to control ourselves is diminished.
In this depleted state, the dieter is more likely to eat chocolate,
the student to watch TV, and the politician to accept a bribe.
In a recent study, Michael Inzlicht of the University of
Toronto Scarborough and colleague Jennifer N. Gutsell offer
an account of what is happening in the brain when our vices
get the better of us.
Inzlicht and Gutsell asked participants to suppress their
emotions while watching an upsetting movie. The idea was to
deplete their resources for self-control. The participants
reported their ability to suppress their feelings on a scale
from one to nine. Then, they completed a Stroop task, which
involves naming the color of printed words (i.e. saying red
when reading the word “green” in red font), yet
another task that requires a significant amount of self-control.
The researchers found that those who suppressed their emotions
performed worse on the Stroop task, indicating that they had
used up their resources for self-control while holding back
their tears during the film.
An EEG, performed during the Stroop task, confirmed these
results. Normally, when a person deviates from their goals
(in this case, wanting to read the word, not the color of
the font), increased brain activity occurs in a part of the
frontal lobe called the anterior cingulate cortex, which alerts
the person that they are off-track. The researchers found
weaker activity occurring in this brain region during the
Stroop task in those who had suppressed their feelings. In
other words, after engaging in one act of self-control this
brain system seems to fail during the next act.
These results, which appear in the November issue of Psychological
Science, a journal of the Association for Psychological
Science, have significant implications for future interventions
aiming to help people change their behavior. Most notably,
it suggests that if people, even temporarily, do not realize
that they have lost control, they will be unable to stop or
change their behavior on their own.