Tuesday, March 16, 2010

Don't eat on a full brain

Here's a interesting study.

Simple experimental design. Take 165 undergraduate students and enroll them in a study you tell them is about memory and where as part of their reward for inclusion, they'll be given a snack. Ask half of them to memorize a 2 digit number and the other half a 7 digit number and once they've memorized their numbers ask them to go into a second room where they are faced with their snack choice - either a piece of chocolate cake or a cup of fruit salad. Track choice and then follow up with an exploration of the students' perceived reasons for making the choice.

The results?

63% of the students who were trying to remember the 7 digit number chose the cake compared with only 42% of those trying to remember the 2 digit number.

Students who chose the cake reported a stronger emotional decision making drive while those who chose the fruit salad reporter a stronger cognitive drive.

Researchers hypothesized that the difference was explicable on the basis of the 7 digit memory group having "lower levels of processing resources" with much of their cognitive brain power being spent on trying to remember their 7 digit number.

Moral of the story?

Don't eat on a full brain.

Shiv, B., & Fedorikhin, A. (1999). Heart and Mind in Conflict: the Interplay of Affect and Cognition in Consumer Decision Making Journal of Consumer Research, 26 (3), 278-292 DOI: 10.1086/209563

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  1. Very nice data to support what I have always told my patients - if you are too busy, lifestyle change is not going to work for you (which by the way is exactly why now an occupational therapist, who teaches time management skills, has been a most valuable addition to our team).

    As a corollary to the study, I would assume that too much information and too many decisions can both lead to overeating. You may recall my post on the "dangers" of variety (http://www.drsharma.ca/how-food-variety-promotes-obesity.html).

    I would also not be surprised if we found that making people read food labels (in their present form) and calculate calories and other nutrients or simply presenting them with more choices on menus will probably make them overeat. Perhaps this explains why adding "healthy" choices to menus actually makes consumers more likely to opt for the "unhealthiest" option.

    Decisions, decisions!


  2. Or perhaps their brains needed more fat and glucose?

  3. Thanks Arya,

    The adding the healthier options to the menu was beautifully explored as "vicarious goal fulfillment".

    Reference and my commments clickable above.

  4. Anonymous11:25 am

    Does this explain the "freshman 15"? Students would routinely be expected to remember more than a 7-digit number - calculus, for example.

  5. Anonymous7:15 pm

    Good cake picture...

  6. Now I'm thinkin' that if I have to work hard remembering 7 digits I want to reward myself with the perceived 'Premium' snack, the cake!

    Two digits? Didn't work to hard, so don't deserve the big prize, so I'll settle for the fruit cup consolation.

    But, I (ir)rationalize as a fat guy, so my judgement is really skewed..heh..heh

  7. I think that no matter what I would have chosen the fruit because it is a choice that is hard-wired into my brain. I would say lifestyle changes can work even if you are stressed or busy as long as you have practiced them. Interesting study!