Bloomberg on Nudging and Leadership

An excellent interview with New York Mayor Michael Bloomberg is in The Atlantic (hat tip to Lee Haber at SCARP for sharing!) today, with some interesting thoughts on American and urban politics throughout. For me, the best bit of the interview was his explanation of his thinking behind the much-discussed soda ban:

“I think it’s government’s job not to ban things but to give you information and let you make the decision. So calorie counts would do that. Portion control is a graphical or physical way of giving you information in terms of how much sugar you’re consuming.”

The ban, which prohibits New York restaurants from selling soft drinks in sizes over 16 ounces, has received significant criticism over its perceived paternalism and the strict nature of the ban. However, Bloomberg (I think correctly) frames the policy differently–not as a restriction on how much soda a customer can buy or drink, but a salient way to convey information about a reasonable threshold of health.

“All we’re saying is that restaurants and theaters can’t use cups greater than 16 ounces. So if you want to buy 32 ounces, you can buy 32 ounces, you just got to carry it back to your seat, or your table, in two cups.”

Why should the amount of soda in your cup matter anyway? If you liked the jumbo size, a free-marketeer might argue, you’ll just get two (or three, or four!) sodas, and all we get for our efforts is some extra trash!

While Bloomberg doesn’t cite the research that underlies this policy, a growing body of research shows that portion sizes strongly influence the amount of food people will consume. In a famous example, groups of subjects were served soup, either conventionally or from bowls that imperceptibly refilled themselves from a vat under the table over time! Researchers measured how much the subjects had eaten: those whose bowls refilled themselves ate significantly more than the control group, but gave similar estimates of how much they’d eaten and how full they were. Essentially, the subjects relied not on their own appetites or dietary goals but on visual cues and simple heuristics, like “finish the portion in front of you.”

Brian Wansink, the author of the study, suggests that most people aren’t very good at estimating volumes of food and drink that they consume, and that portion sizes provide cues that can bias the amount we eat or drink. And without regulation, Bloomberg notes, consumption cues are being decided to maximize profits, not health:

“But to say to the public — the public says “I have a right to have my bottle of soda in any size I want” — no! You only have the right to buy soda in the size of the bottle that the manufacturer decides it is in his or her interest to sell.”

Bloomberg’s regulation, while appearing heavy-handed, is actually a great example of choice architecture–it preserve’s people’s freedom to consume what they want, while providing a handy cue towards what we might call an ‘optimal’ level of consumption. (One caveat is that consumer might end up paying more for two 16oz sodas than they would for one 32oz drink, in which case the regulation is a bit more of a shove than a nudge.)

As a last bit of wisdom on the subject: when the interviewer brought up popular opposition to the move, Bloomberg was unswayed, and in fact quite dismissive of the notion (here, anyway) that policy nuance should be subject to a public opinion veto:

“Leadership is about doing what you think is right and then building a constituency behind it. It is not doing a poll and following from the back…

[That’s not] good business or politics, because people aren’t good at describing what is in their own interest. If you say to somebody, “How many times do you turn the page?” and then go and stand on the other side of the room where they don’t notice you, and count, you will get a very different number from what they said they did. That’s true with everything. And — the obligation — what leaders should do is make decisions as to what they think is in the public interest based on the best advice that they can get, and then try and build a constituency and bring it along.”

The full interview, including great discussion of issues from restaurant licensing to bike lanes to Occupy, is here.


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