I have written a few times about factors that affect willpower. Willpower is the name that we give to the mechanisms (most of which involve the frontal lobes of the brain) that prevent us from carrying out a behavior we really want to perform.
Over the past several years, there have been a number of studies showing that if you make people work hard to control their behavior, then they have difficulty continuing to use willpower in a later situation that calls for preventing behavior. The idea that willpower is a resource that can be used up is called ego-depletion. It has been studied extensively by Roy Baumeister, Kathleen Vohs and their colleagues.
A paper by Veronika Job, Carol Dweck, and Gregory Walton in the November, 2010 issue of Psychological Science suggests that one factor that affects whether you show ego-depletion effects is whether you believe that willpower is a limited resource.
In one study, they asked people a number of questions about willpower. Some people gave answers suggesting that they believe that willpower is a limited resource. Other people gave answers suggesting that willpower is actually an unlimited resource.
Later in the study, people did a difficult task that was either relatively easy or one that was hard. The easy task involved crossing out all of the letter es on a page of written text. The harder task asked people cross out all of the ‘e’s for a while, and then switch so that they crossed out every ‘e’ except for the ones that were followed by another vowel. This task is difficult, because people have to prevent themselves from doing a behavior that they had already built up some habit to perform.
After doing this task, people performed a Stroop task. In the Stroop task, people see words naming colors that are written in a colored font. People have particular difficulty naming the color of the font when the word is the name of a different color. For example, people are prone to make mistakes when they see the word “yellow” written in red font.
Putting all this together, people who believed that willpower is a limited resource made more mistakes on the Stroop task following the difficult letter-crossing task than following the easy letter-crossing task. That is, these people showed the typical ego-depletion effect where doing one difficult self-control task makes it hard to do a second.
In contrast, the people who believed that willpower is essentially unlimited did equally well no matter which letter-crossing task they did. That is, those people who think that willpower is unlimited did not show the ego-depletion effect.
Now, it is possible that there are just differences between people. Some people have limited willpower resources and others don’t. On that view, it isn’t that your beliefs about willpower affect your performance, but rather that your beliefs about willpower reflect your actual abilities.
To explore this possibility, a second study actually manipulated people’s beliefs about willpower by using a biased questionnaire. One version of the questionnaire got people to agree with statements suggesting that willpower is a limited resource (“Working on a strenuous mental task can make you feel tired so that you need a break before accomplishing a new task.”) A second version used a questionnaire that got people to agree with statements suggesting that willpower is unlimited (“Sometimes working on a strenuous mental task can make you feel energized for further challenging activities.”)
After these questionnaires, the groups did the same tasks as before.
In this study, the group that was biased to believe that willpower is limited did more poorly on the Stroop task following the difficult letter-crossing task than following the easy one. In contrast, the group that was biased to believe that willpower is unlimited did just as well on the Stroop task regardless of which letter-crossing task they did.
Taken together, these studies suggest that people’s beliefs about their own willpower are one factor that affects how effective their willpower will be. The more that you believe that willpower can keep you from doing things that you don’t want to do, the more likely you will be to use your willpower successfully.
All this suggests that it is well worth believing in willpower.