Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Akira Miyake

Second Advisor

Margaret Campbell

Third Advisor

Alice Healy

Fourth Advisor

Tiffany Ito

Fifth Advisor

Yuko Munakata

Abstract

Self-control has become an increasingly popular topic in psychology in recent decades. The main goal of this dissertation is to evaluate the current conceptualization and measurement of self-control by focusing on a popular yet controversial phenomenon known as ego-depletion and the strength model of self-control that has been used to explain the phenomenon. More specifically, in this dissertation, I report the results of two studies—a review and an empirical study—that jointly tested some of the core assumptions widely held by the proponents of the strength model.

I first conducted a systematic review of the ego-depletion literature, which included 63 articles and 148 individual studies of the ego-depletion phenomenon. In this review (reported in Chapter 2), I identified key conceptual and methodological problems that have made it difficult for ego-depletion studies to derive clear and explicit hypotheses. Findings of this review demonstrated the prevalence of such problems in research practices in the current ego-depletion literature.

In the second main part of this dissertation, I empirically addressed some of those major issues, primarily the lack of independent validation of commonly used laboratory self-control tasks as good measures of self-control (Chapter 3). Specifically, I conducted a large-scale individual differences study to evaluate some of the core assumptions of the strength model, such as the assumption that all self-control tasks commonly used in the ego-depletion research tap a common underlying process (presumably, self-control resources). Findings indicate that although there is something common among these tasks, the commonality does not appear to reflect self-control.

On the basis of the results of the systematic review and the individual differences study, I discuss concrete ways to move the field forward in the final synthesis chapter (Chapter 4). My discussion of possible ways forward focuses primarily on future ego-depletion research, but more generally, this final synthesis also helps pave new ways to better understand the nature of self-control and specify how it operates.

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