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Can Self-Control Temporarily Reduce Brain Power? | Creyos (formerly Cambridge Brain Sciences) Blog
Cognitive Assessment

Can Self-Control Temporarily Reduce Brain Power? | Creyos (formerly Cambridge Brain Sciences) Blog

Published: 22/12/2017

Written by: Mike Battista

Your wellbeing often depends on controlling your thoughts, subduing impulses, and holding back your emotions. But here’s the thing with self-control: it’s hard. This observation has led to the resource theory of self control, which proposes that every time you subdue your desires, you deplete a limited resource. If you control yourself too much, too quickly, you run out of this resource—a state called ego depletion—and you’re worse at holding back.

Ego depletion doesn’t quite lead you to become The Incredible Hulk, but, if the theory is correct, it can make you more impulsive, leading to behaviours like taking that second helping of cheesecake even if you shouldn’t, or clicking on that movie spoiler even though you haven’t seen it yet.

In a psychology lab, there is (unfortunately) no cheesecake, but there are tasks that require controlling your attention, such as our Double Trouble task. When you make people control themselves, do they become worse at cognitive tests that require attentional control?


How Bad Science Leads to Better Science

This theory sure sounds intuitive. And when it’s put to the test in small studies, it seems to be true—people who are forced to exercise self-control do worse at attentional control tasks.

However, if you’ve read other posts on this blog, you know that I can be skeptical of claims based on a handful of studies, especially if they seem a little too intuitive and simple. This is one of those sounds-good theories, like power posing and countless others, that could very easily turn out to be bull when put to the test.

When scientists examine the ego depletion evidence more closely, there are indeed some issues. Some attempts to replicate the results have failed, and reviews of the literature are plagued by small studies and incomplete data due to unpublished studies. This is usually where we conclude “oh well, I guess the evidence for ego depletion is mixed at best. If only someone would do a large study that fixes the flaws of previous studies, and is published no matter what the results are.”

In this case, researchers at Texas A&M University did exactly that, in a recent pre-registered, pre-printed paper: Ego Depletion Reduces Attentional Control.


Conserve Your Self-Control, Make Fewer Mistakes

In the new study, ego depletion was manipulated by having participants write a story about a recent trip. In the normal condition, they wrote the story without any restrictions. In the controlled writing condition, they had to write the story without using the letters A or N. As you can imagine, it requires a lot of self-control to hold back on the impulse to write freely. If the theory is true, writing with those restrictions ought to lead to ego depletion.

After the story-writing task, participants took some cognitive tests involving attention, such as a Stroop task (similar to Double Trouble).

Participants with depleted egos did worse on the tasks—specifically, by making more errors. They didn’t seem to change the speed of responses, however; working at the same pace, they simply messed up more when they’d recently exercised self-control.

Does it mean you should start letting your impulses run wild until you really need some control? Probably not—the effect is small, so probably won’t make a big difference in real life. I also wonder how specific the effect is to self-control, or if any difficult task just makes it harder to focus on subsequent tasks. Looks like we need more studies after all.


This post was written by Mike Battista, a staff scientist at Creyos (formerly Cambridge Brain Sciences).

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