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Akrasia Solved!

January 28, 2010

NPR has this bizarre story on chocolate cake and why you can’t resist chocolate cake when trying to remember a lot of numbers. It’s cribbed from an earlier WSJ article on the same issue. Since I try to avoid reading the WSJ, I’m only just learning of it now.

Evidently, some people think that your brain can “fill up” like a trash bin, and that willpower works kinda like your muscles.

In one experiment, led by Baba Shiv at Stanford University, several dozen undergraduates were divided into two groups. One group was given a two-digit number to remember, while the second group was given a seven-digit number. Then they were told to walk down the hall, where they were presented with two different snack options: a slice of chocolate cake or a bowl of fruit salad.

Here’s where the results get weird. The students with seven digits to remember were nearly twice as likely to choose the cake as students given two digits. The reason, according to Prof. Shiv, is that those extra numbers took up valuable space in the brain—they were a “cognitive load”—making it that much harder to resist a decadent dessert. In other words, willpower is so weak, and the prefrontal cortex is so overtaxed, that all it takes is five extra bits of information before the brain starts to give in to temptation.

Spare me. The numbers “took up valuable space in the brain”? That’s ridiculous, unless she’s speaking metaphorically. Oh, she must be speaking metaphorically, since the brain is a physical object and the numbers are…wait for it…frigging numbers. They don’t take up any space at all.

Maybe she means that the students were preoccupied with trying to focus on a random seven-digit strong of numbers when some chocolate-cake wielding seductress assaulted them and tempted them to do something that they might otherwise not have done. How hard is that to understand? It doesn’t have anything to do with space being taken up. It has to do with chocolate cake, focusing on something other than chocolate cake, and getting a wee bit piggy. But wait, it gets better.

The willpower-as-muscle metaphor should also change the way we think about dieting. Roy Baumeister, a psychologist at Florida State University who has pioneered the muscle metaphor, has demonstrated in several clever studies that the ability to do the right thing requires a well-fed prefrontal cortex.

In a 2007 experiment, Prof. Baumeister and his colleagues found that students who fasted for three hours and then had to perform a variety of self-control tasks, such as focusing on a boring video or suppressing negative stereotypes, had significantly lower glucose levels than students who didn’t have to exert self-control. Willpower, in other words, requires real energy.

Um, okay, which they’re measuring by looking at what people do... so maybe it’s the case that what takes real energy is doing something, whether will power is involved or not. And how is this supposed to help us think differently about dieting?

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One comment

  1. This seems like bad science reporting.

    Richard Holton, in his new book (which I enjoyed, and which has some interesting bits on weakness of will) uses the muscle metaphor as well. It seems like the wrong metaphor to use, especially since feeding subjects glucose or showing them something humorous brings the ‘muscle’ right back to normal.

    Further, the cognitive load studies might just show this: that in people who both like chocolate cake and who are cognitively taxed, what Timothy Wilson calls the adaptive unconscious operates without much moderation from that part of the brain which would see the cake, pause, and think, ‘maybe I shouldn’t.’ This doesn’t seem like a case of the brain ‘giving in to temptation,’ but rather of some subsystems of the brain working normally (see cake: eat cake), while others (which might resist the urge to eat the cake) working to remember numbers instead of what they would normally do.



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