Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type


Type of Thesis

Departmental Honors



First Advisor

Akira Miyake


Ego depletion was previously found to be a robust effect and generally could be explained by one of two theories: the strength model of self-control and mindset theory. Yet, much recent research has faced a replication crisis; the original effect has been elusive, even with replication efforts with large sample sizes. The current study examined 90 university students on their mind-wandering and inhibitory control errors by conditional group (depletion vs. control). I correlated these outcome measures with other measures which ascertained subjects’ beliefs regarding the capacity of their willpower. This project tested two popular accounts of the ego depletion effect: the strength model and the mindset theory. There were significant differences between the two groups on the basis of the depletion task being rated as more difficult, effortful, and frustrating than the non-depleting task. Additionally, motivation between the two groups were not statistically different. Despite such group equivalency in motivation and one condition being significantly different from the other, no significant ego depletion effect which would support the strength model was found. Additionally, although some outcome measures were moderately correlated with participants’ belief about their willpower, there was no evidence for the moderating influence of willpower belief on the ego depletion effect. Thus, this research provides no evidence in support of either the strength model or the mindset theory of ego depletion.