Although it’s a fleeting desire, people do actually want to be healthy. When they’re motivated to maintain or improve their health, people will seek out information to do so and act accordingly. Unfortunately, the mind is a divided system of competing motivations, and “be healthy” is not one motivation to pick fights. This idea, that health is a losing motivation for many people, can explain why obesity is such a problem in a country with cheap, calorie-dense foods. The widely accepted proposal to address this is to trigger another seemingly more powerful motivator: money. The prevailing logic is that people will buy less unhealthy products if those products are more expensive. If we tax alcohol, tobacco, and sugar, people will buy less of these products and, hopefully, drink less, smoke less, and consume fewer calories.
When Mayor Bloomberg of New York City proposed taxes on large sugary drinks, it was exciting because it seemed like policy makers might finally be taking the advice of psychologists and behavioral economists. It’s common to think that medicine and engineering provide drugs, treatments, structures and technologies that realistically impact our lives, but that behavioral sciences aimlessly document how people think and behave in counter-intuitive ways. A beautifully engineered iPhone 5 might drive computing and communication into a new age, while a study priming men to be measurably more creative seems nothing more than an interesting read over coffee at the kitchen table. In fact, behavioral science research supplies necessary tools for addressing human problems (see Scott Atran’s argument here).
Despite the potential to inform public policy, behavioral science, like natural science, requires empirical evidence. Just like approving the safety of a plane requires more than good computer simulations, or a safe drug requires more than thorough animal trials, real confidence in policy aimed at changing public behavior requires randomized experiments and field studies (see Dave Nussbaum’s piece here, and Richard Thaler here). I think that the proposal to tax soft drinks falls short of actual applied behavioral science. Though there is good theory to expect vice taxes to reliably decrease the behaviors at which they’re targeted, the empirical data just aren’t there (or the effects are small, see Fletcher, Frisvold, & Tefft, 2010).
A good example of randomized trials that could inform policy comes from research at Cornell. Brian Wansink and colleagues published their findings from a field study in the eastern United States (Wansink, Hanks, Just, Cawley, Sobal, Wethington, & Schulze, 2012). Over 6 months, they tracked the purchases of over 100 households, half of which received a 10% tax on low nutrient: calorie foods during the treatment period. They found that although the treatment group (compared to control) purchased significantly less taxed, unhealthy foods during the first month, these differences disappeared by three months and purchases were unchanged by six months. Moreover, among those in the treatment group, households that reported to be regular beer and fruit juice purchasers actually increased their purchases of these products.
It is findings like these that, if communicated effectively, would shock a committee assembled to discuss vice taxes. The point is not to suggest that we avoid policy designed to nudge people into make better decisions. Rather, we should inform our decisions about such behavioral change, and who better to inform us than the experts on behavior themselves—economists, psychologists, sociologists and the like. Alas, my fear is that paying for social experiments to inform policy is not a high priority, much like “be healthy” is not a strong motivation.
References
Fletcher, J. M., Frisvold, D., & Tefft, N. (2010). Can soft drink taxes reduce population weight?. Contemporary Economic Policy, 28(1), 23-35.
Wansink, B., Hanks, A., Just, D., Cawley, J., Sobal, J., Wethington, E., & Schulze, W. (2012). From Coke to Coors: a field study of a sugar-sweetened beverage tax and its unintended consequences. Available at SSRN.
