‘depletion is the psychological sum of these feelings, of all the decisions you made that led to that moment. The decision to get up early instead of sleeping in, the decision to skip pastries every day on the way to work, the decision to stay at the office late to finish a project instead of leaving it for the next day (even though the boss was gone!), the decision not to skip the gym on the way home, and so on, and so forth. Because when you think about it, you’re not actually too tired to choose something healthy for dinner (after all, you can just as easily order soup and sautéed greens instead of beef lo mein and an order of fried gyoza), you’re simply out of will power to make that decision.’
Bloomberg’s proposal makes clever use of what economists call “default bias.” If you offer a choice in which one option is seen as a default, most people go for that default option. People who are automatically enrolled in a retirement plan, for instance, are more likely to stay with their original plan than those who choose plans for themselves. In countries where people have to choose to be an organ donor, most people aren’t donors; in countries where people have to actively say they don’t want to be an organ donor, most are donors. The soda ban makes sixteen ounces or less the default option for soda drinkers; if they want more, they’ll have to make an extra effort.
(via The Economics of Michael Bloomberg’s Large-Soda Ban : The New Yorker)