early 20 years ago, psychologists Roy Baumeister and Dianne Tice, a married couple at Case Western Reserve University, devised a foundational experiment on self-control. “Chocolate chip cookies were baked in the room in a small oven,” they wrote in a paper that has been cited more than 3,000 times. “As a result, the laboratory was filled with the delicious aroma of fresh chocolate and baking.”
Baumeister and Tice timed the students in the puzzle task, to see how long it took them to give up. They found that the ones who’d eaten chocolate chip cookies kept working on the puzzle for 19 minutes, on average—about as long as people in a control condition who hadn’t snacked at all. The group of kids who noshed on radishes flubbed the puzzle test. They lasted just eight minutes before they quit in frustration.
The authors called this effect “ego depletion” and said it revealed a fundamental fact about the human mind: We all have a limited supply of willpower, and it decreases with overuse.
So willpower was not like muscles but like a glass of water. Hmm.
Psychologists discovered that lots of different tasks could drain a person’s energy and leave them cognitively depleted. Poverty-stricken day laborers in rural India might wear themselves out simply by deciding whether to purchase a bar of soap. Dogs might waste their willpower by holding back from eating chow. White people might lose mental strength when they tried to talk about racial politics with a black scientist. In 2010, a group of researchers led by Martin Hagger put out a meta-analysis of the field—a study of published studies—to find out whether this sort of research could be trusted. Using data from 83 studies and 198 separate experiments, Hagger’s team confirmed the main result. “Ego depletion” seemed to be a real and reliable phenomenon.
Sense trouble right away then. These studies are all covering behaviours of different entities in different situations. Big theories, big dangers…
But that story is about to change. A paper now in press, and due to publish next month in the journal Perspectives on Psychological Science, describes a massive effort to reproduce the main effect that underlies this work. Comprising more than 2,000 subjects tested at two-dozen different labs on several continents, the study found exactly nothing. A zero-effect for ego depletion: No sign that the human will works as it’s been described, or that these hundreds of studies amount to very much at all.
This isn’t the first time that an idea in psychology has been challenged—not by a long shot. A “reproducibility crisis” in psychology, and in many other fields, has now been well-established. A study out last summer tried to replicate 100 psychology experiments one-for-one and found that just 40 percent of those replications were successful. A critique of that study just appeared last week, claiming that the original authors made statistical errors—but that critique has itself been attacked for misconstruing facts, ignoring evidence, and indulging in some wishful thinking. More.
Social science theories are getting debunked so often, it’s best to assume that the field has the science status of popular relationship magazines.
Readers, we are frustrated too. This stuff takes up a lot of space in our inbox, but it is hard to ignore a firehose.
Something’s happening. For the first time in many years, people are asking about the credibility of what is labelled as science. Will that trend spread?
See also: Credibility crisis: Psychology’s wishful thinking
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