Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

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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