Jonah Lehrer’s engaging book, How We Decide examines how different parts of the brain work to influence our decision-making processes. He vividly explains how the prefrontal cortex can quite easily become overloaded by cognitive demands and cause us to make different decisions than we would otherwise.
In one experiment (also described in this WSJ article and NPR segment), participants were divided into two groups. One group was asked to memorize a two-digit number, and the other was asked to memorize a seven-digit number. (George Miller’s classic paper The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information demonstrated that for most people, seven digits are the limit of our brain’s short term memory. To memorize a seven-digit number requires much more repetition and effort than does a two-digit number.) Participants were then asked to walk down the hall to a second room where they would recite the number they had memorized.
Along the way, they were met by a researcher who offered them their choice of fruit salad or chocolate cake as a snack. 59 percent of those trying to remember a seven-digit number chose the cake, as compared with only 37 percent of those memorizing a two-digit number. Lehrer explains:
Distracting the brain with a challenging memory task made a person much more likely to give in to temptation . . . According to the Stanford scientists who designed the experiment, the effort required to memorize seven digits drew cognitive resources away from the part of the brain that normally controls emotional urges. (151)
In addition, your brain requires two things to survive: oxygen and glucose. Even small drops in glucose levels can “inhibit self-control, since the frontal lobes require lots of energy in order to function” (Lehrer 152). In other words, there’s a reason why you feel tired and hungry after intensive intellectual work.
What does this have to do with getting through the end of the semester? I took away two relevant lessons from this chapter of Lehrer’s book:
- Your brain will undoubtedly get overloaded from fatigue as well as cognitive demands. Simply being aware of this fact and postponing important decisions can be useful.
- If you know from experience that junk food calls your name loudly during marathon grading sessions, stock up ahead of time on healthy snacks and go easy on yourself when you indulge.
Speaking personally: I have almonds and protein bars in my desk drawer, but gazing into my crystal ball, I foresee the likelihood of potato chips in my future. How about you? Let us know in the comments!
[Creative Commons licensed image by flickr user Marshall Astor]