The Chocolate Machine That Can Improve Your Willpower

What if someone told you they had invented a machine that sits on your desk and strengthens your self-control? What if they further told you that that machine worked by feeding you chocolates? You would assume that person was a small child, perhaps, or a late-night TV pitchman.

At a tech conference a week ago, however, a team of German psychologists and designers introduced to the world just such a device: the Chocolate Machine, “a transformational product to improve self-control strength.” The Chocolate Machine is very simple: a tube reminiscent of a tall sleek Pez dispenser that, every 40 to 60 minutes, releases a chocolate ball onto a person’s desk. The recipient could then eat it or put it back into the machine. When the subjects started the study, they were told that putting the chocolate back into the machine would help build their willpower. The machine had a counter that kept track of how many times the user put chocolates back in the tube. That’s it.

The concept behind the machine is something called ego depletion, a model for how self-control and decision-making works, most associated with the American psychologist Roy Baumeister. In the ego-depletion model, willpower is like a muscle: It can tire over time. In one famous study, Baumeister had people eat radishes while leaving a plate of chocolate-chip cookies untouched in front of them. Then he gave them an unsolvable puzzle to do. The people who had denied themselves the chocolate chip cookies, he found, gave up on the puzzle faster than those who had been able to indulge their sweet tooth. Forcing themselves to eat the radishes had depleted their willpower.

The good news is that willpower, also like a muscle, can be strengthened with exercise. That’s what the Chocolate Machine is supposed to do: each chocolate put back in the machine is like a set of sit-ups for your self-control.

According to Marc Hassenzahl, a psychologist who helped design the Chocolate Machine, the device was an attempt to design something whimsical but effective—something that would work not by stick and carrot but by a sort of gentle suasion. “It’s not rewarding good behavior and punishing bad behavior,” he says. “It’s like a friend who’s commenting on your behavior and saying: ‘You’re doing it again; wouldn’t it be better if you did it this way instead?’”

There are as yet no plans to mass-produce the Chocolate Machine, but Hassenzahl already envisions a whole category of devices meant to prod people toward virtue in similar ways—he’s also built a reading light that has to be periodically touched to stay on, reminding users that the light isn’t free. He calls this category of non-coercive behavior-modification design “an aesthetic of friction, rather than an aesthetic of convenience.”

So does the Chocolate Machine work? The experimental group that Hassenzahl and his collaborators tried the machine on was small: just 24 people, with 10 using the machine and the rest in a control group. Of those 10, however, seven found that the machine improved their self-control, and they proved more persistent at doing difficult mental challenges than the control group.

“It’s not Nobel Prize material,” Hassenzahl says, “but it’s encouraging.”

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