The Psychology of Soda Bans


I've been thinking a fair bit about paternalism recently, since as the father of a one-year-old I have to do a lot of paternalizing (apparently spell check and I disagree on whether that’s a word). In general, I’m a strong proponent of allowing kids to make their own choices, but sometimes it doesn’t take long for theory to meet practice, especially when they’re choosing activities like climbing down the stairs or eating crayons (I knew I should have bought the non-toxic kind). There is obviously a point at which some things have to be off limits. For New Yorkers, Daddy Bloomberg decided that the limit was at sixteen ounces of soda. If you want more than that you’re going to have to get a whole other cup. Bloomberg’s ban provoked angry protests from New Yorkers who insist that they aren’t children and that they can make their own soda choices. In this week’s New Yorker, James Surowiecki argues that while it’s true that the soda ban is paternalistic, it could still be very effective at reducing soda consumption. And I believe he may be right – the research he reviews is compelling – but there is other research that suggests that the ban could backfire, or at least that heavy handed paternalism may not be the best way for the Mayor to achieve his goal.

Where Surowiecki is certainly right, is in his claim that people’s desires can be incredibly malleable. Our preferences are strongly influenced by all sorts of things we are usually not even aware of. As Surowiecki explains it:

An executive at the American Beverage Association has dismissed [Bloomberg’s] plan, saying that “150 years of research finds that people consume what they want.” Actually, the research shows that what people “want” has a lot to do with how choices are framed.

The evidence that Surowiecki marshals to support this claim are convincing. Making sixteen ounces the default and forcing someone to actively choose to get two separate cups if they really want all that soda is likely to be effective. Taking away the biggest option is also likely to transform the sixteen ounce size from “medium” to “large”. And, just having less soda in front of you is likely to make you feel satisfied with less soda. Mayor Bloomberg’s hope is, presumably, that the furor over the ban will subside over time and New Yorkers will be left with a choice set that is likely to make them healthier.

The potential downside, though, is that there is also evidence that imposing choices on people, as Bloomberg is doing, can have just the opposite effect. Every parent knows that the best way to get a kid interested in something is to tell them they aren’t allowed to have it. The psychological term for this phenomenon, introduced by Jack Brehm in the 1960s, is reactance. As Columbia University’s Sheena Iyengar put it in an article in the Dallas Morning News:

Most of us would probably agree that we’d be better off if we drank less soda, but any government action designed to control consumption puts us on alert.


If we want to implement a sweetened beverage tax and maximize its effectiveness, the best approach would be to dissociate it from the larger issue of individual choice and focus on its immediate practical benefits, such as the revenue it produces.

The key point is that, whatever approach you favor, it’s probably best to avoid drawing attention to the fact that you’re forbidding people from doing something. We all know how that worked out for Adam and Eve, and Romeo and Juliet may have quickly lost interest in one another if their families had just left them alone. That’s why in their book, Nudge, Dick Thaler and Cass Sunstein favor a subtler approach. As Thaler commented in response to Bloomberg’s soda ban:

To state the obvious: a BAN is not a NUDGE.The opposite in fact. So don't blame Bloomberg's ban on large soda cups on us.

— Richard H Thaler (@R_Thaler) May 31, 2012