The science of willpower

Whether it’s dieting, working through boring tasks, or sticking to an exercise plan, willpower seems to be required in every facet of life. And the more you’ve got, it seems, the better off you are.

The science of willpower is a bit confusing. It’s currently under intense scrutiny, after years of every study seemingly agreeing with how willpower works. Let’s explore what we know (and don’t know) about willpower, and what this means for getting your work done and avoiding temptation.

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Why we think willpower is finite

One of the biggest leaps forward in the scientific study of willpower came in the 1990s, from a psychologist called Roy Baumeister. Baumeister and his colleagues conducted an experiment that has since been cited over 3,000 times, which seemed to prove that willpower is a finite resource that we can run out of.

The study had participants wait in a room with two plates of food: freshly-baked cookies and radishes. Some participants were told to only eat the cookies, while others were only allowed to eat the radishes.

After this waiting period, the participants were given a puzzle that, unbeknownst to them, was impossible to solve. The researchers measured how long participants kept trying to solve the puzzle before giving up.

What happened, which supported Baumeister’s hypothesis, was that participants who’d not been allowed to eat the cookies (and therefore, supposedly, had used up some of their willpower on resisting the cookies) gave up on the puzzle. Those who’d only been allowed to eat radishes gave up after an average of eight minutes, while those who ate the cookies (and a control group who only did the puzzle) lasted nineteen minutes on average.

This study seemed to prove that using up willpower on one temptation can mean we have less leftover for other tasks. And other studies have backed up the finding. Over 100 studies, in fact, have shown some effect of what researchers call “ego depletion,” where using up willpower on one task leaves less available for a future task.

Bolstered by this success, Baumeister even published a book based on his research: Willpower: Rediscovering the Greatest Human Strength.

Willpower might not be limited after all

But the findings aren’t as iron-clad as they seem. There have also been plenty of studies that failed to replicate Baumeister’s results. And in 2010, Evan Carter from the University of Miami looked into a meta-analysis of 198 experiments and 83 studies that appeared to show the ego depletion effect was real. But Carter found the analysis only included published studies that supported Baumeister’s results. The studies in the analysis also contradicted each other in how they measured self-control.

Carter’s re-analysis found no evidence of an ego depletion effect. Nor did he find one in a second meta-analysis he completed including 48 unpublished experiments.

Unsurprisingly, these results caused a flurry in the scientific community. Ego depletion and the notion of willpower being finite were accepted ideas by now, but Carter’s work demonstrated that the “proof” of these concepts was flawed.

In 2014, the Association for Psychological Science aimed to resolve some of this confusion by creating a set of experiments to be done by different labs to test definitively for ego depletion. Martin Hagger, author of the original meta-analysis Carter examined, worked on the project, and Baumeister consulted on the methodology. A set of computer tests were chosen to test willpower (for instance, not clicking on particular letters in words that flashed on-screen), which had produced a strong ego depletion effect in a previous study.

Out of the 24 different labs that ran the same experiment in various languages, only two found a significant effect of ego depletion. One even showed a negative effect, where the participants’ willpower seemed to be boosted by the original willpower test. When combined, the set of experiments didn’t show any ego depletion effect. Baumeister still believes the effect is real, and could be shown with slightly different methodology, though if he’s right it may mean the effect only shows up under very specific circumstances.

But the negative ego depletion effect has been replicated in other research. One study tested for ego depletion in participants from India, Switzerland, and the U.S. and found a reverse effect in some people. This study asked participants to complete two tasks such as solving a maze, editing some text, or completing a word search.

For Indian participants, the more difficult the first task (and therefore, presumably, the more willpower required to stick at it until it was done), the better they performed on the second task. Most Western participants showed the opposite—they struggled more with the second task if the first was harder than they did when starting with an easy task.

For the Indian participants, the more strongly they believed that mental effort is energizing (which is a more popular cultural belief in India than in Western countries), the stronger the reverse ego depletion effect. Researchers believe it’s possible that what you believe about willpower can affect how your willpower works, which may account for the struggle to replicate Baumeister’s results. Research has shown that if you believe your willpower is unlimited, rather than finite as Baumeister asserts, expending willpower on one task won’t affect your performance on a subsequent task.

How to improve your willpower

The scientific community is still on shaky ground when it comes to willpower. Nobody is quite sure if the effect of ego depletion (or the reverse) is real, or under what circumstances it can be reliably reproduced.

In the meantime, the best research we have about willpower suggests a few ways we can work on improving our own.

Believe a dip in willpower is temporary

What you believe about willpower appears to be the key to how much willpower you can actually expend. Those who believe a dip in willpower is only temporary, and can be overcome, are more likely to bounce back than those who worry about lacking willpower as a permanent condition.

It’s not easy to change our beliefs, but try reminding yourself whenever you’re feeling low on willpower that it’s temporary, and you’ll have more in the future. Try not to tell yourself you’re a person with low willpower all the time, as it may become a self-fulfilling prophecy.

Treat willpower as an emotion

Michael Inzlicht, professor of psychology at the University of Toronto, suggests we treat willpower as we would an emotion. Our emotions tell us important information about our circumstances, if we pay attention to them. They can help us understand how best to look after ourselves and what our needs are.

Listening to our willpower, then, can help us understand when we’re not in a great space to be doing something difficult, or when we’ve got plenty of self-control to spare, and can handle something we might otherwise avoid.

Believe mental effort energizes you

As the study involving Indian participants showed, ingrained beliefs about expending willpower and mental effort can affect how we experience those situations. Believing that it’s energizing to expend mental effort and self-control can make those things true.

Again, changing your beliefs isn’t easy. But it can make a huge difference to how you experience the struggle of using willpower, so it may be worth the effort. Try to remind yourself in tough situations that holding out, working hard, and using your willpower will energize you and help you relish these challenges in the future.


With the scientific community divided over how willpower works, it can be a confusing topic to explore. But despite the struggle to replicate results and prove how willpower works definitively, we can still look to science for ideas on improving our own willpower—even if that really means just feeling less exhausted by expending mental effort, rather than actually having more willpower in the first place.

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Belle B. Cooper

Belle is an iOS developer, writer, and co-founder of Melbourne-based software company Hello Code. She writes about productivity, lifehacks, and finding ways to do more meaningful work.

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