So you’re ambling along one summer afternoon and pass by your local park. Nothing new, but now there’s a sign posted at the entrance: the park is holding a 5K next weekend. You decide to take the reins on your life and spend the interim period jogging sections of the course. It’s more exercise than you’ve done in a month, maybe two, but you did it, and now you’re hooked. The 5K comes and goes, and soon you’re finding yourself running purely for its own sake.

You turned one event into a healthy lifestyle, all because of one tiny "nudge."

What's In A Nudge?

Nudges are deceptively complex. They’re built in to our environment, latently pushing us in certain directions and doing the decision-making for us. Some nudges are active, like the hypothetical 5K sign or the ongoing futility of New York mayor Michael Bloomberg trying to ban large sodas. Some are passive, like the way organ donation programs are structured. In either case, nudges exert great power over how we live our lives, in ways that are both positive and negative, so shouldn’t it make sense we begin looking for them?

The hypothetical 5K mentioned above is actually based on a real study that was recently performed by the Rand Corporation. Scientists selected 50 parks in Los Angeles, gave each of them $4,000, and told them to use the money however they wanted. The goal was simple: “Given that parks are intended to serve local communities, successfully addressing the underutilization of parks may require community input and participation,” the authors wrote.

Out of all the new policies implemented between 2007 and 2012, far and away the most common was the introduction of park signs. Nearly all parks spent half of their money on installing new signs, most of them at the entrance of the park. Twenty-eight percent of the money went to materials and labor for activities, and a fifth funneled into promotional incentives, such as giveaways.

While most of the park usage increased among people who were already frequent visitors, the study suggested to the researchers that motivation may not be the linchpin to exercise. “There is a large body of evidence indicating that environmental cues influence and change individual behavior,” they noted, “including physical activity.”

What the team found was essentially the power of a nudge. Signs are active nudges. They deliberately interrupt your brain’s stream of perception to present you with information about the environment, which, it’s implied, you should act on.

No parking on Sunday.

Please curb your dog.


The effectiveness of a park’s sign hinges on its ability to drum up motivation — to cause the schlubby pedestrian to rethink the time he spends on the couch, and to lace up a pair of cross-trainers instead. But active nudges are harder to execute than passive nudges. Whereas passive nudges allow you to keep doing nothing, active nudges require you make an effort. You have to change something, and in order for you to change your behavior, you have to want to change it. Decision-making, curiously, is much easier when you don’t know you’re doing it.

Sign Me Up

Take organ donation. In the United States, 85 percent of people support organ donation, according to an oft-cited Gallup poll from 1993. Despite this, less than half had decided to do so, and even fewer — 28 percent — signed off on their driver’s license to become organ donors. In fact, the same effect took place in countries around the world. Denmark, Germany, and the United Kingdom all had dismal donor rates; meanwhile France, Poland, and Portugal all had near total inclusion. The countries opting in showed no political similarities to one another and no opposition to the countries opting out. They were just grouped randomly. So what caused the discrepancy?

As it turns out, the pattern wasn’t random. And like most passive nudges, it wasn’t intuitive. Whether people opted in or out to become organ donors relied on only one variable: the design of the DMV form.

Psychologists Eric Johnson and Daniel Goldstein first discovered the phenomenon. Countries that used a form where applicants had to actively check a box saying “Yes, I want to be an organ donor” showed far lower rates of participation than countries whose default was “No, I do not want to be an organ donor.”

“Many people would rather avoid making an active decision about donation, because it can be unpleasant and stressful,” the team wrote in a recent issue of Science. Rather than actively scan a set of forms for opportunities to be included in a program, the majority of people were found to appeal to the default. They assumed any pertinent information was already presented to them as an active choice, letting their eyes float effortlessly over the organ donation box, which, depending on the country, had vast unintended consequences.

“The tradeoff between errors of classification and physical, cognitive, and emotional costs,” the team concluded, “must be made with the knowledge that defaults make a large difference in lives saved through transplantation.”

Here, the power of a nudge is subtle. In the study of L.A. parks, it was overt. But both were powerful motivators for change — one decidedly more poignant — although, in the right context, active and passive nudges have the potential to affect decision-making in equal measure. Policy decisions rely on an informed public’s active choice to uphold or strike down proposed legislation. Mayor Michael Bloomberg propositioned New York City earlier this year with an active nudge toward, what he believed to be, healthier living through bans on sugar. The courts disagreed. The nudge was misguided and inconsistent, they said. So they shot it down.

A Tag-Team

The truth is, active and passive nudges work in tandem. The park that posts a sign goading pedestrians to hike a trail is the same park that can plant flowers along the trails or flank it with water fountains to make the walk naturally more appealing, for reasons other than fitness. Healthy living doesn’t have to be intentional.

Researchers from the Netherlands, the U.K., and Canada offer a final example, which they published in an editorial in the Journal of Environmental and Public Health.

“Curtailing the provision of sweets at the supermarket checkout removes cues to consumption in the environment," they wrote, "in effect, passively nudging consumers away from unhealthy choice by removing it." However, they point out an important caveat in the active-passive tag team, which is that "curtailing availability of cues or enforcing menu labeling requires action at the policy level,” too.