When I write an article for Cognitive Daily, I follow a similar pattern nearly every time. First I carefully read the journal article I’ll be discussing. Next I take a break and work on something else. Then I get myself a caffeinated beverage and some kind of sweet treat (usually it’s chocolate-covered raisins but today I’m in a coffee shop having just finished a toffee almond bar). Often it won’t be until ten or fifteen minutes after I’ve eaten that I really get into a groove with the writing. Then I write the entire post, usually for an hour or two straight, pausing only to produce the graphics and demos accompanying the story. The hard part is finished, and the final formatting, editing, and posting can be done at leisure, sometimes even while I’m working on other projects or getting the kids started on their homework.
The part that really requires self-discipline is the writing itself. Usually I disconnect the internet in my house, or even head out to a coffee shop (one of the few remaining with no internet access) to remove all possible distractions. The self-control necessary for writing is well-known, and many writers, such as the eminent lexicographer Samuel Johnson, have discussed how excruciating the writing process is for them (Johnson once said “No man but a blockhead ever wrote, except for money.”). But self-control is required for many more mundane tasks as well. Try to watch this silent movie (QuickTime Required) of me reading this post while ignoring the words that flash periodically in the lower-right corner of the screen:
It’s not easy, is it? It almost feels like work, just to avoid reading. While reading is a mental process too, it feels like we’re expending more energy avoiding reading than we would to do the reading itself.
Maybe there’s something to that feeling. Research led by Roy Baumeister has found that people who’ve resisted eating cookies gave up sooner on a task requiring persistence compared to those who succumbed to temptation and ate the cookies. Other research has associated low blood glucose levels with poor performance on the Stroop task — another task that requires people to avoid reading. Is it literally true that the sugar in our blood fuels our ability to control our impulses?
Matthew Gailliot, along with Baumeister and six other researchers, asked 103 psychology students to fast for three hours before watching a video like the one I showed above. Half the students were told to ignore the words, while the rest weren’t required to exercise any self-control. Blood glucose levels were measured before and after this task. The students exercising self-control had significantly lower glucose levels after watching the movie, while the other students did not. In another experiment, students performed the Stroop task after watching the movie. The students who had to resist reading the words performed significantly worse on the Stroop task; their lower blood glucose levels after watching the movie and avoiding reading seemed to impair performance.
In another experiment, a new group of 62 students watched the movie, again divided into groups who watched normally or controlled their attention by avoiding reading. Then everyone was offered a glass of Kool-aid lemonade. Half the lemonade was sweetened with sugar, while half was sweetened with Splenda, which does not affect blood glucose levels. Since glucose takes about 10 minutes to be absorbed by the brain, everyone was given a 10-minute distractor task, then given an 80-item Stroop task. Here are the results:
As you can see, when the students consumed glucose, they performed just as well on the Stroop task, whether or not they had had to exercise self-control while watching the movie. But students who didn’t consume any glucose performed significantly worse on the Stroop test.
Gaillot’s team repeated these experiments several times, with tasks ranging from avoiding displays of racial prejudice to dealing with thoughts about death. In each case, the results supported the idea that self-control literally relies on glucose. When blood glucose is depleted, we’re less able to exert self-control. The researchers say that the brain has a limited reserve amount of glucose, which allows us to handle the initial task demanding self control, whether it be watching a movie without reading accompanying text, or avoiding fattening snacks. Once that glucose supply is depleted, self control becomes much more difficult, across an array of different tasks.
The researchers are careful to point out that consuming sugar isn’t the only way to increase blood glucose levels — it may be that eating protein bars or complex carbohydrates offers better long-term results. However, my method of using chocolate to help give me the self-discipline to write CogDaily posts has only rarely failed me, for a test period of over three years!
Gailliot, M.T., Baumeister, R.F., DeWall, C.N., Maner, J.K., Plant, E.A., Tice, D.M., Brewer, L.E., Schmeichel, B.J. (2007). Self-Control Relies on Glucose as a Limited Energy Source: Willpower Is More Than a Metaphor. Journal of Personality and Social Psychology, 92(2), 325-336. DOI: 10.1037/0022-35220.127.116.115