Willpower and self-control are not resources that can be depleted.
According to popular beliefs, self-control is akin to a muscle that gets fatigued with frequent use. This concept has taken root in psychology and is often discussed in productivity blogs and everyday conversations. For example, after a long day filled with choices, we might say we are "exhausted," as if we have spent all our internal reserves.
In psychology, this phenomenon is referred to as ego depletion, where acts of self-control are thought to drain mental energy. For instance, if you declined dessert at lunch, it may be harder to resist the urge to binge-watch a series in the evening. This concept is intuitively understood and often serves as an excuse for resting after a stressful day when our internal resources seem depleted.
But what if this is not the case? What if willpower does not actually get depleted?
The ego depletion theory was proposed in the late 1990s and quickly gained popularity. It was based on numerous laboratory studies suggesting that each act of self-control uses the same limited internal resource (or "willpower muscle"). Once this resource is depleted, we become more impulsive and make less thoughtful decisions.
This theory found its way into bestsellers and even politics. For example, Barack Obama, the former President of the United States, explained that he wore the same suits to save energy for making important decisions. This idea proved useful for explaining mental exhaustion and developing strategies for conserving willpower.
However, over time it became clear that things are not so simple. In a number of experiments related to ego depletion, participants performed one self-control task and then moved on to a more challenging one. According to the theory, their performance should have worsened on the second task. This can be compared to focusing on work in the morning and then struggling to maintain attention on tasks in the afternoon.
Nevertheless, meta-analyses that combined the results of several studies did not confirm the validity of this theory. Numerous attempts to replicate the results in different laboratories showed ambiguous or even negative outcomes. The question of what exactly gets depleted remained open. Initially, depletion was linked to blood glucose levels, but this explanation was debunked. The more psychologists tried to uncover the causes of ego depletion, the more vague their conclusions became.
Proponents of the ego depletion theory continued to argue that previous studies were not complex enough. My colleagues and I decided to create a model that would allow ego depletion to manifest. If willpower is indeed like a muscle, then the longer a person works on a challenging task, the more fatigued they should become. We conducted a 35-minute online study where participants completed two tasks. The first was a challenging numerical version of the Stroop test, requiring quick naming of the number of digits on the screen. The second task required switching focus between general and specific details.
Contrary to the ego depletion theory, participants adapted over time, showing improvements in speed and accuracy, without demonstrating systematic declines in performance even after prolonged effort.
Interestingly, the difficulty of the test varied: some participants completed a more challenging version with frequent conflicts, while others did a simpler one. If willpower truly worked like a muscle, then the challenging version should have depleted participants more quickly. However, the facts showed the opposite: those who completed the more difficult test maintained their pace and even sometimes accelerated.
If the ego depletion model does not explain how self-control works, alternative approaches must be sought. One such alternative is the metacontrol theory, first proposed by cognitive psychologist Bernhard Hommel. This concept suggests that the brain operates along a continuum between two states: persistence and flexibility. One can think of this as a car with two gears: persistence is the mode for climbing, while flexibility is for smooth driving and exploring new routes.
When the brain operates in persistence mode, it narrows the focus of attention and becomes more resistant to distractions, which helps tackle challenging tasks. In contrast, in flexibility mode, the brain is more open to new ideas and better adapts to changing conditions.
Neither mode is "better"; it depends on the context. In everyday life, you may notice these shifts: you focus on work and then switch to a more flexible mode while socializing with friends.
Persistence is important when writing scientific papers or resisting temptations, while flexibility is beneficial for creative tasks and solving unexpected problems. The brain naturally switches between these states, especially when tasks become difficult or rewards are uncertain.
From the perspective of metacontrol, "depletion" may actually be a transitional phase. After prolonged effort, the brain may shift to flexibility mode not because resources are depleted, but to adapt to new conditions. Evolutionarily, our ancestors likely survived due to their ability to easily switch between modes rather than getting stuck on one task.
The metacontrol theory offers a more accurate explanation for changes in performance and aligns with modern neurobiological data. It links changes in cognitive mode to dopamine activity in various brain regions that regulate the balance between persistence and flexible adaptation. Dopamine levels may influence how we perceive tasks: at high levels, we are more focused, while at lower levels, we are open to new ideas.
These findings are important for understanding effort, self-discipline, and failures in everyday life. When we encounter "setbacks" or fatigue, it may not signify weakness but rather a natural mode switch in the cognitive system.
If willpower is viewed as switching between modes, then moments of fatigue may reflect adaptive changes rather than depletion. These changes may be influenced by context, motivation, and the environment.
Sometimes a short break is not a failure but an opportunity for recalibration.
In other words, when you experience mental fatigue, it does not always mean you need to exert more effort. Sometimes what we perceive as depletion is a result of the system's adaptation. In such cases, it may be wiser to take a pause, change strategies, or reboot. This could involve, for example, taking a short walk after working on a challenging report or changing the type of task.
If we abandon the metaphor of "willpower as a muscle," how can we envision willpower? It can be seen as a car that shifts gears depending on the environment, goals, and internal feedback, constantly assessing the effectiveness of the current strategy based on sensations, progress, and expected rewards.
This does not mean that discipline is unimportant, but improving willpower may require a deeper understanding of how the brain works. More nuanced psychological models are needed that reflect the actual workings of the brain, rather than how we would like it to work.
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