Date of Award


Degree Type


Degree Name

Doctor of Philosophy in Clinical Psychology


Clinical Psychology



First Advisor

James O. Prochaska


Understanding multiple health risk behavior change may contribute to the prevention of chronic illness. The present study examined drivers of behavior change over time within individuals with health behavior risks who were at risk for two behaviors. Participants were middle school students from a randomized controlled trial conducted across 20 middle schools within the state of Rhode Island using two transtheoretical model tailored, computer-delivered interventions in the school setting. Participants received an alcohol prevention program or an energy balance program. Analyses were conducted with participants who were at risk for both physical activity and fruit and vegetable intake (N = 1401). A series of chi-square analyses, one-way between subjects ANOVAs, and MANOVA models were conducted to examine whether (1) Treatment (received energy balance intervention), (2) baseline Stage of Change, (3) Effort, and (4) Severity predicted the number of behaviors that an individual changes (no behaviors, one behavior, or two behaviors) at three follow-up time points (12, 24, and 36 months). Additionally, demographic effects were examined in the context of participants at risk for multiple health behaviors. Treatment, Stage of Change, Severity, and Effort at baseline, were all significantly related to the number of behaviors changed at a certain time point over the course of the study- 12, 24, or 36 months, or across multiple time points. Treatment demonstrated the greatest consistency across behaviors and time points, with more participants in the treatment condition being in the paired action group (change on two behaviors) at each time point (12, 24, and 36 months). Furthermore, age, was the only consistent demographic effect across time points. Findings shed light on the mechanisms of multiple behavior change within individuals, providing a deeper understanding of what impacts the number of behaviors that an individual changes over time.



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