Date of Award

Spring 1-1-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology & Neuroscience

First Advisor

Tiffany Ito

Second Advisor

Bernadette Park

Third Advisor

Joshua R. Correll

Fourth Advisor

Naomi Friedman

Fifth Advisor

Stefanie Molborn

Abstract

This work examines the relationship between self-control and marijuana use. Marijuana is one the most widely available, most frequently used, illicit drugs in the United States today. Despite the changing legality of marijuana, there are still many concerns about the negative impact of marijuana use on both physical and mental health. Self-control, or the ability to pursue long-term goals while ignoring short-term distractions, has been associated with a variety of positive life outcomes. Conversely, low self-control has been associated with negative life outcomes and most importantly, drug use and abuse.

In this dissertation, I examine the relationship between marijuana use and self-control. I confirm that there is a relationship, and then I explore the nature of that relationship. The focus of this dissertation is an examination of two competing hypothesis that may explain the relationship between self-control and marijuana use. These two hypotheses differ in how appetitive motivation, such as a person’s urges to use marijuana or the extent to which one associates marijuana with pleasure, relates to both self-control and marijuana use. In my first hypothesis, appetitive motivation moderates the relationship between self-control and marijuana use, and self-control interacts with appetitive motivation in predicting marijuana use. My second hypothesis is that appetitive motivation, instead, mediates the relationship between self-control and marijuana use.

These hypotheses and relationships are examined in two studies. In Study 1, I cross-sectionally examine the relationship between self-control and appetitive motivation in predicting intentions to use marijuana in the future. Study 2 expands upon Study 1, examining how self-control and appetitive motivation relate to marijuana use over the course of a three-year longitudinal study. Together, these two studies suggest that appetitive motivation, specifically one’s urges to use marijuana, may mediate the relationship between self-control and marijuana use. There is little evidence suggesting that the appetitive motivation moderates the relationship between self-control and marijuana use. This mediation model contradicts many current models of drug use and has critical implications for understanding how to control one’s marijuana use. Addressing appetitive motivation, rather than self-control, may be the key to controlling or reducing marijuana use.

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