Around this time each year, my family and I, as well as Jews around the world, celebrate Passover, the holiday that commemorates the exodus of the Jewish people from slavery in Egypt. Like many Jewish holidays, this one features prominently a range of colorful symbolic foods and the ingestion of a large prolonged meal. And also like many Jewish holidays, this one ends with me fielding the mostly rhetorical question from one or more of my relations, “Why did I eat so much?”, quickly followed by a lament along the lines of, “I have no self-control around food!” This is a relatable feeling. We’ve all had an experience with overeating at some point in our lives. But is this failure of self-control caused by us not having “enough” self-control, or could other factors matter even more?
The view that many people hold is that self-control is a quality that remains stable throughout a person’s life, similar to IQ or personality. Research in psychology has also generally espoused this view, for example, by famously showing that children who were able to resist a marshmallow for a brief period of time in favor of two marshmallows later went on to do better in school and other important domains as adults compared to children who were unable to resist the temptation. However, upon closer inspection the idea of self-control as a stable trait begins to break down. For one, a person’s level of self-control tends to wax and wane over the course of the day, suggesting that self-control is less like a mental capacity such as intelligence and more like a fluctuating resource such as physical energy. In fact, even the researchers who conducted the classic marshmallow experiments interpreted their findings in terms of learned strategies rather that innate abilities, suggesting that the reason children who delayed did better later in life is because they had been taught when and how to deploy effective self-control techniques.
In light of the fluctuating nature of self-control, the question of failure is not about who is good or bad at self-control but rather about when or under which conditions self-control is more or less likely to be successful. We know, for example, that factors such as negative mood, fatigue, and alcohol play a large part in self-control failure. So I often tell my relatives that the four glasses of wine that we drank during the Passover meal contributed at least as much to our gluttony than any weakness of will. One especially well-studied factor that decreases self-control is previous effort. All else being equal, a second self-control attempt following an initial one is more likely to fail than one that comes after a relatively restful period. The diminishing effect of one self-control attempt on others is so common that it’s been given its own name, “ego depletion,” and has now been found in over 100 studies. On account of ego depletion, my relatives who spent most of the evening biting their tongues to avoid reawakening some old argument would be more likely to overeat during the meal than those who happily aired their grievances.
Though psychology researchers began their quest to understand self-control by tracking down the factors that reduced it, they’ve altered course lately to seek out ways to improve it. Just as negative mood can diminish self-control, positive mood can enhance it. Just as exerting self-control initially reduces the ability to do so later, restorative activities such as prayer, meditation, and self-affirmation amplifies it. As with so many psychological concepts, self-control is also highly sensitive to our beliefs about ourselves. For example, people who were led to believe that they had ample energy—even though they had just completed a difficult self-control task that had caused “ego depletion” in others—did just fine on subsequent self-control tasks. Similarly, people who believe that self-control is unlimited rather than “depletable” do not conform to the ego depletion pattern. The implication for overeating is that self-control around food may be a self-fulfilling prophecy: Your “actual” level of self-control is far less important in determining your success than how much self-control you think you have or how effective you believe yourself to be in using it.
My informed take at this point is that self-control is indeed a resource, but a renewable, psychological one. We’ve known for a long time that goals that are motivated from within—for reasons that are personally important to us—are more likely to succeed than those that are motivated from without. This broad rule appears to apply to self-control specifically in the case of desires for unhealthy food and other indulgences. Temptations that we want to overcome are indeed easier to overcome than those that we feel we have to overcome. Succeeding at self-control is more about the desire rather than the technical skill to do so. At Passover, we know how to stop eating in a literal sense; we just don’t know how to think about overeating in a way that motivates us to stop. Perhaps by next year science will have even more ways to help us do that.
Note: This article is cross-posted at The Conversation.