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Design Defined: What Is a ‘Nudge’ in Product Design?

(This post is based on the video, “Nudge,” in the Design Defined: Design Principles Explained series.)

Have you ever given someone a nudge in the right direction? People tend to make decisions unconsciously. A nudge helps redirect them toward a better one.

The nudge theory was popularized by Richard Thaler and Cass Sunstein in their 2008 book, Nudge: Improving Decisions About Health, Wealth, and Happiness. Here’s how they describe it:

“A nudge, as we will use the term, is any aspect of the choice architecture that alters people’s behavior in a predictable way without forbidding any options or significantly changing their economic incentives. To count as a mere nudge, the intervention must be easy and cheap to avoid. Nudges are not mandates. Putting fruit at eye level counts as a nudge. Banning junk food does not.”

Simply put, it’s a little push that makes the user think or do something they might not instinctively do.

Nudge Theory in Design

One of Thaler’s favorite illustrations of “nudge” dates back to the early 1990s at the Schiphol airport in Amsterdam, where the floors in the men’s restrooms were getting a little too sticky.

An economist who worked at the airport had the idea to etch an image of a housefly into each urinal just above the drain. The result was an 80 percent reduction in “spillage.” Sphinx, the manufacturer of the urinals, reported that the fly reduces cleanup by 20 percent on average. It turns out when men see a target, they want to hit it.

Nudge is a concept rooted in behavioral science that describes how minor design changes can markedly affect individual behavior.

The fly-in-the-urinal nudge was successful (and has been copied around the world), because it follows four important rules of behavioral design:

1. Align incentives with desired behaviors.
2. Provide clear, visible, and immediate feedback to reinforce desired actions.
3. Simplify and structure choices when decision-making parameters are complex.
4. Make goals and performance status clearly visible.

Here are some more examples of effective design nudges:

  • In Sweden, a blood donation service was afraid of running dry. They decided to send texts to blood donors whenever their blood was used to save someone’s life.
  • A paper towel dispenser by Saatchi and Saatchi is an example of an overt nudge. It integrates an environmental message into a paper towel dispenser, which has a cut out in the shape of South America. It’s filled with green paper towels, which illustrate the continent’s green rainforest canopy. As paper towels, colored green, are dispensed, the user sees the continent drained of its greenness.
  • A toilet paper roll by Shigeru Ban is a subtle nudge. Its square tube provides friction when turning, and the resistance gently nudges the user to take less paper.
  • A speed bump counts as a nudge as do other traffic-calming and pedestrian-safety devices, such as a dancing traffic light in Germany.
  • These footprint decals for escalators, proposed by a London designer, nudge commuters to stand right/walk left.
  • Gamification in digital design is another place to find nudges. The Nest Leafs that pop up in the Nest thermostat app are rewards earned by energy-saving behavior.
  • Nudges can be entertaining — like those dancing traffic lights and these playful, hopscotch and free-throw-line decals in front of garbage cans in Lucerne.
  • And right here in Philadelphia is the world’s first behavioral design team embedded within a health system — the Nudge Unit at Penn Medicine. They determined that patients are more likely to get (and take) their medication when it’s less expensive. So they worked with the group who runs Penn Medicine’s IT system to change the default option in the system used by doctors so generics would appear before brands in the dropdown menu when they’re prescribing medication. Almost overnight the generic prescribing rate went from 40-70% to 99%.

Nudging for Good, and Not for Evil

Nudges that benefit the greater good are more positive than others, but there is some controversy about the ethics of nudges that are designed purely for private profit.

Thaler’s mantra is, “If you want to get people to do something, make it easy. Remove the obstacles.”

In an op-ed for the New York Times, he supplemented that mantra with three principles to guide the principled use of nudges:

  • All nudging should be transparent and never misleading.
  • It should be as easy as possible to opt out of the nudge, preferably with as little as one mouse click.
  • There should be good reason to believe that the behavior being encouraged will improve the welfare of those being nudged.

Thaler notes the existence of troublesome nudges, such as phishing practices, in the private sector. He calls these evil nudges, “sludge.” They’ve also been called “dark nudges.” Sludge, or dark nudges, are ones that encourage people to do the wrong thing. Procedures that accidentally or deliberately encourage inertia count as sludge. Voter ID laws are a good example as they’re calculated to passively disenfranchise.

Designing a default option into a user experience can either be a nudge strategy or a sludge strategy, depending on the operator’s intentions. Some countries make their citizens organ donors by default. That’s a nudge. But the tactic can be used against consumers. According to a survey, 70% of consumers in the U.S. continued to pay for unwanted subscriptions because they forget to cancel before the renewal date. They’re opted in automatically when they subscribe.

Can you think of a design element, either physical or digital, that has nudged you in the right — or wrong — direction?

Learn about more product design principles when you download our free eBook, Design Defined, vol 1.