Wednesday, April 10, 2013

Jedi Mind Tricks

Let’s start with an exercise.  Think of the last 2 digits of your social security number.  Got it?  Now, at what year did Albert Einstein emigrate to the United States?

Did you guess 1933?  If so, you are the smarty pants exception to the rule.  Chances are, if your social digits are high, you guessed high, and vice versa.  This is an example of a neat behavioral economics mechanism called “anchoring,” in which our decision making processes are affected by information around us.

In the realm of public health, behavioral economics can help us make the right decisions.  We often know what’s good for us. But we can’t always do what we want to do.  I don’t want to eat a bag of leftover Smart Food by myself.  I don’t even like popcorn.  And yet I do.  As I’ve discussed before, public health sometimes helps us out of these jams by taking away opportunities for us to make mistakes.  But sometimes public health gives us the choice to decide.  Then helps us to make the right decisions. 
(One of my favorite institutions in Brunswick, ME)

One example of this help comes from Dr. Sara Bleich at Johns Hopkins.  In a wicked cool experiment, Bleich and her team posted 3 different messages about soda at neighborhood bodegas. 

“Did you know that a bottle of soda or fruit juice has about 250 calories?” 

“Did you know that a bottle of soda or fruit juice has about 10% of your daily calories?” 

“Did you know that working off a bottle of soda or fruit juice takes about 50 minutes of running?

Do these statements do anything for you?  Which statement is a bigger deterrent for you?  I’m an easy target, but the exercise one rings most powerful to me.  (Full disclosure: Because of my terribly indiscriminate I'm-a-hungry-grad-student-diet, I'm easily shamed and susceptible to suggestions.  This usually results in buying many overpriced bananas by the cafe checkout counter.)  Bleich and her team tracked the buying behavior of adolescents in the stores over a 6 months period.  They found that the signs worked.  Looking at the 3 strategies as a whole, the odds of buying a “sugar sweetened beverage” (soda or fruit juice) decreased by 44% after they posted the signs, as compared to before.  Looking at the 3 methods separately, the exercise information was significantly associated with a decrease in purchase. 

Even if quinoa and kale aren’t a part of your regular diet, the evidence on the negative health effects of consuming too much sugar (i.e. empty calories), especially in adolescents, is weighty and obvious*.  Yet information alone can’t improve population health.  Public health relies on brilliant folks like Dr. Bleich to figure out the right tricks to employ to help us make the right decisions.

*Never an inopportune time for a DHem plug.  Thanks to Jesse for the reminder.


  1. You can sub-title this..."Lets be real" So interesting how we know things, but then decide we don't know them because it is easier.
    This is also the point though where some of my very conservative (and nameless) friends would say that the government or "Public Health" needs to stay out of their refrigerator and let them make the decisions that they want.
    When it comes to personal decisions that do effect public health in the "weighty and obvious" way, is public health personally invasive in it's attempts at intervention or does the corporate benefit outweigh the perceived bossy signage?

  2. Ah, this is so interesting, Sarah! (also, I was thinking a recipe/post from you would be a great follow up to this) I had thought that the signs were at least a more passive way of intervening-- the choice is yours-- and didn't think of it as bossy (maybe b/c, like I said, I'm really suggestible to these signs already). I'm going to ponder on your question. I'm sure there are more nuanced studies about this.