SPOTLIGHT: Is self-control a limited resource?

BIG PICTURE: In his 2013 book, How to Fail at Almost Everything and Still Win Big, Dilbert cartoonist Scott Adams declares: “Science has demonstrated that humans have a limited supply of willpower.”

He cites three sources in a footnote. One I’m unable to locate, the other two aren’t especially enlightening (see here and here). But Adams isn’t mistaken. In 2012, the American Psychological Association released a 19-page report titled What You Need to Know about Willpower: The Psychological Science of Self-Control.

This document tells us that “scientists have made some compelling discoveries about the ways that willpower works.” We’re told “a large and robust body of supporting evidence” exists, and that “a growing body of research shows that resisting repeated temptations takes a mental toll” (my italics).

Even though we’re advised on page five that “willpower depletion” is merely a theory, the “Key Points and Conclusions” section on page 16 throws caution to the wind: “Studies show that repeatedly resisting temptation drains the ability to withstand future enticements,” we read (my italics). The bullet points that follow then proceed to treat willpower depletion as an established fact.

But the supposedly robust evidence began to crumble in 2014. After reexamining the published data for this widely-accepted idea, researchers Evan Carter and Michael McCullough concluded that “the depletion effect is actually no different from zero.” A year later, they published a paper with two other people that declared: “We find very little evidence that the depletion effect is a real phenomenon.”

In 2016, things got uber serious. The results of a study whose entire purpose was to replicate the early experiments that had seemed so convincing were published. Two dozen labs from around the world participated. The conclusion: “if there is any effect, it is close to zero.”

The notion that our supply of willpower is limited and shouldn’t be wasted on trivialities is, in my view, immensely useful. Rather than being a hard fact, it’s an important psychological insight. When Adams declares that the “trick to eating right is to keep willpower out of the equation,” I’m totally with him. If I don’t bring potato chips home from the supermarket, I won’t be tempted to eat them in a single sitting.

If an idea is helpful in our daily lives, that’s good enough. Whether it’s possible to design a scientific experiment that tracks the successive diminishment of our willpower as we’re tempted again and again is another matter entirely.

TOP TAKEAWAY: When talking about what “science has demonstrated,” humility is advised. Much of today’s science will end up in tomorrow’s dustbin.

LINKS:

How to Fail at Almost Everything and Still Win Big: Kind of the Story of My Life Scott Adams

• in the literature, ‘willpower depletion’ and ‘ego depletion’ are often used interchangeably
• the 2016 failure-to-replicate study is here
• Carter and McCullough’s 2014 paper is here
• the 2015 “very little evidence” paper is here
• see also Daniel Engber’s great overview article: “Everything Is Crumbling: An influential psychological theory, borne out in hundreds of experiments, may have just been debunked. How can so many scientists have been so wrong?”

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