Vending machines are rarely a person’s first choice for a meal—or even a snack—but those who live or work far from other options might find the automated dispensers to be a part of their daily lives, for better or worse.

From a nutrition standpoint, the offerings of vending machines are almost always “for worse.” Though the offerings are improving as vending machines carry semi-fresh offerings, for the most part, they’re still home to dozens of preservative-laden, sugary or salty snacks that remain both cheap and popular.

However, health psychologist Brad Appelhans has employed a sinister tactic in a tweaked vending machine that he hopes will condition people to pick the healthier options over the more familiar and more popular junk food offerings.

How?

By making them wait much longer for the junk food than for the more nutritious fare.

Appelhans noticed that people he worked with didn’t use the automatic door because, once the button is pressed, a three-second delay occurs before the door actually opens. Impatient as they are, people systematically chose to manually operate the door rather than wait for the convenience of having the door open automatically.

Inspired by what he saw, the psychologist implemented the Delay to Influence Snack Choice (DISC) vending machine, which forces people who choose an unhealthy selection to stand by for an interminable 25 seconds before their choice is dispensed. The logic being that vending machines, especially in schools and workplaces, are used by the same people repeatedly, so the conditioning would be more effective than if the users weren’t repeat customers.

It may not be “the vending machine of the future,” as this outlet puts it, but it does offer more insight into how people decide on food choices:

So far, the data shows that the delay doesn’t adversely affect total sales, but has seen a 3-5 percent increase in healthy snack selection since the DISC machines have been implemented throughout Chicago. Appelhans said that a 25 cent “tax” on unhealthy choices served as a more powerful deterrent, but at a greater cost, stating, "Unlike the discount, the delays didn't harm the overall revenues of the machine. Places want people to have more nutrition, but they don't want to lose revenue. So the time delay might be a nice way to have it both ways."

Though 3-5 percent may not seem like a sea change in eating habits, considering the only tweak here is making people wait, further changes in technology and additional healthy offerings could see that number continue to rise, demonstrating to the world that vending machines aren’t just home to sugary and salty junk foods.