McDonald's is losing traction in America.

The brand's sales have been declining as customers seek out fast-casual options like Chipotle. Slower customer service, tensions with franchisees, and an overloaded menu have also hurt the brand.

But McDonald's discovered a secret in France that could help it gain traction in America: self-serve kiosks.

The kiosks are now in all of its French restaurants. Customers input and pay for their order at the ATM-like station, and then pick up the food at the counter. People like using them because they can skip lines and take their time.

McDonald's CEO Steve Easterbrook told investors this week that the kiosks have three major benefits.

1. Customers like the choice.

Easterbrook says that about 40% of customers in France use kiosks to order during busy hours.

"We give customers a choice, and they just welcome choice," Easterbrook said.

McDonald's self-serve kiosk in France. Business Insider / Pamela Engel

2. Workers are less stressed.

The self-serve kiosks help keep lines down, according to Easterbrook.

"It takes on the stress away from the front counter, and therefore you divide some of the pressure, some of the load during the busiest times," Easterbrook said.

The kiosks also help with accuracy because customers are inputting orders themselves.

A McDonald's near the entrance of a Metro station in Paris. Reuters

3. People spend more money.

The kiosks allow customers to browse a colorful menu and select the items they want to order. Easterbrook says this makes customers feel less rushed, leading to them buying more items and spending more money.

There's also a psychological reason that could lead to customers who use the kiosks buying more food.

"Researchers have long found that shoppers spend more the further they get from handling actual currency and tend to better remember cash transactions," writes Kyle Stock at Bloomberg Businessweek. "These tendencies help explain why credit card balances tend to bloat and why casinos use chips in place of money."

McDonald's has been testing self-serve tablets for its "Create Your Taste" custom burgers in California.

McDonald's "Create Your Taste" tablet. Foodbeast

McDonald's will utilize kiosks, smartphones, and wearable devices in America soon, Atif Rafiq, chief digital officer at McDonald's, told Fast Company earlier this year.

The brand is planning even higher-tech measures.

"You could walk up, tap your phone to it, and sync your account via an app. From there, the screen would not just show a stock menu, but provide your order history, and offer Amazon-like recommendations," according to Fast Company.

Using kiosks and other technology could help McDonald's drive sales, improve perception, and speed up customer service.