Would You Rather Walk a Mile or Walk For 30 Minutes?

| Tue Apr. 23, 2013 11:18 PM EDT

Aaron Carroll reports today on a recent study about the effect of calorie labeling on restaurant menus. Four different menus were randomly assigned to different diners:

(1) a menu with no nutritional information, (2) a menu with calorie information, (3) a menu with calorie information and minutes to walk to burn those calories, or (4) a menu with calorie information and miles to walk to burn those calories. 

There was a significant difference in the mean number of calories ordered based on menu type (p = 0.02), with an average of 1020 calories ordered from a menu with no nutritional information, 927 calories ordered from a menu with only calorie information, 916 calories ordered from a menu with both calorie information and minutes to walk to burn those calories, and 826 calories ordered from the menu with calorie information and the number of miles to walk to burn those calories.

For the moment, let's assume the study was done properly and these results are actually meaningful. Why would people respond so differently to minutes walked vs. miles walked? Here are a few possibilities:

  • Minutes don't sound so bad. People vaguely figure they'll do a few hundred minutes of walking just in the ordinary course of their day.
  • "Miles" strikes people as inherently more athletic. It's the kind of distance you hear in the Olympics.
  • Most of us walk so little that we overestimate just how long a mile is.

To be honest, the first option is the only one that really sounds plausible to me. What am I missing? Assuming this isn't just a statistical aberration, what would account for the large difference in response to minutes vs. miles?