Do not assume willpower is a fuel tank that inevitably runs empty
A popular theory says exerting self-control on one task leaves less for the next, so willpower must be rationed. A coordinated replication across 23 laboratories and 2,141 participants found an effect close to zero. Avoid treating “I used up today’s willpower” as an established explanation, or paying for courses built around stockpiling it.
What it takes
Nothing. The change is in how you explain your behavior.
What you may gain
A preregistered multilaboratory replication used the standardized sequential-task procedure from Sripada and colleagues: first perform a task requiring self-control, then perform another. Across 23 laboratories and 2,141 participants, the pooled ego-depletion effect was very small, d=0.04, with a 95% CI of −0.07 to 0.15 that included zero. The authors discussed what this meant for the model of self-control as a limited resource.
Context & considerations
The disputed claim is that self-control is a resource that gets used up, not that people become tired. Inadequate sleep and prolonged work can reduce performance; see the sleep and working-hours entries in chapter 3. Approaches with randomized evidence include moving temptations farther away and writing specific when, where, and if–then plans. Most entries in this chapter count money; this one concerns time and mental effort, with no attempt to convert one into the other.
Research & references
Hagger MS, Chatzisarantis NLD, Alberts H, et al. (2016). A Multilab Preregistered Replication of the Ego-Depletion Effect. Perspectives on Psychological Science, 11(4), 546–573. https://doi.org/10.1177/1745691616652873.