A 25-second delay caused customers to rethink their junk food selection, and opt for a more nutritious item.

Credit: Getty Images

When you're trying to decide between Twizzlers and trail mix, 25 seconds could make all the difference, a new study suggests.

Researchers found that people made healthier choices at vending machines when there was a brief time delay. Installing machines with this technology in schools and workplaces could result in healthier snacking, the authors say, without affecting sales.

The demand for “healthy vending” is huge, says lead author Brad Appelhans, clinical psychologist at the Rush University Prevention Center—but removing junk food entirely from machines can result in dissatisfied customers and lost profits. In their quest for a better solution, Appelhans and his colleagues focused on ways machines could disincentivize their least healthy options—like, for example, making people wait.

“We’ve known for a long time that there’s an association between the delay until you receive a reward and how influential it is to your decision,” says Appelhans. “The longer you have to wait for something, the less desirable it is.”

That’s because humans have a strong preference for instant gratification, Appelhans continues. And when it comes to making dietary choices, that means sugary, fatty junk food often wins out.

“The health benefits of making a healthy food choice generally aren’t realized for many years, whereas your choice to have a delicious donut is rewarded right away,” says Appelhans. “If we can delay the junk food relative to the healthier option, we're essentially using that principal of delayed gratification in reverse.”

For their study, the researchers deployed experimental vending machines to three locations for about 14 months, during which more than 32,000 snack sales were recorded. Some of the machines functioned normally, while others instituted a 25-second delay on snacks classified as less healthy.

To be considered healthy, a food had to meet five of seven criteria: have less than 250 calories per serving, 35% or fewer calories from fat, less than 350 milligrams of sodium per serving, no trans fats, less than 5% of daily value of saturated fat per serving, more than 1 gram of dietary fiber per serving, and less than 10 grams of added sugar per serving.

To get our best wellness advice delivered to you inbox, sign up for the Healthy Living newsletter

In the time-delay scenario, customers who chose a less healthy item were given a 25-second countdown, during which they were free to select a healthy option to be delivered immediately. Earlier experiments suggested that 25 seconds was something of a sweet spot, says Appelhans—long enough to change some people’s minds, but not so long that it annoyed customers to the point where sales were compromised.

And for some people, the intervention worked. Depending on the machine’s location, the delay yielded a 2% to 5% increase in the proportion of purchases from healthy snacks, says Appelhans. Considering that there are 1.3 million vending machines across the United States, he says, such an increase could have a significant impact.

The researchers also tested the effects of a 25-cent tax on less healthy items and a 25-cent discount on healthier ones. These scenarios also increased the proportion of healthy snacks purchased, says Appelhans, but a time delay has the added advantage of not costing consumers more or reducing revenue.

So can this 25-second rule be used to make healthier choices anytime you’re mulling over snack or meal choices? Appelhans is skeptical: Without someone or something enforcing the time delay, he says, it’s unlikely to be as effective.

“Once you require somebody to exert self-control in the moment, it becomes a lot harder,” he says. “If they had willpower to count to 25, it probably wouldn’t be that hard for them to make a better choice right off the bat.”

The researchers would, however, like to study the effects of time delay on food choices in other contexts, such as fast food restaurants and online grocers. Their current findings were presented today at the Society of Behavioral Medicine's Annual Meeting & Scientific Sessions in San Diego, and have not yet been published in a peer-reviewed medical journal.

Appelhans’s group has applied for a patent on their technology, and they hope to find a commercial partner to bring their invention to the market. “Vending machines are the biggest source of high-calorie, nutrient-poor foods in the United States, and there’s a huge need for strategies to make them healthier,” he says. “We think this could have a major impact, but first we need the industry to get on board.”