Date of Award

2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Psychology

Department

Psychology

First Advisor

Wayne Velicer

Abstract

Health behavior research reveals that individuals vary in their general readiness to change their behaviors, as well as their attitudes and beliefs about that change. Adolescents are an important population for health behavior change interventions because the choices and behaviors early in life can have long-term health impacts. A large (N=42158), school-based Transtheoretical Model (TTM) randomized trial evaluated two tailored, computer-delivered multiple behavior interventions designed to impact energy balance behaviors, including physical activity, fruit and vegetable consumption, and TV viewing, or substance use, including smoking and alcohol. The study took place over a four-year period, with intervention points during grades six through eight and a follow-up assessment in grade nine. Main outcomes from this study indicated that students in the energy balance intervention effectively initiated and maintained energy balance behaviors in addition to reducing smoking and alcohol acquisition, despite no direct treatment for smoking and alcohol prevention. To better elucidate the process of behavior change, and to inform future interventions on how students at different levels of readiness to change respond to the intervention in relation to a comparison condition, an examination of the patterns and transitions in stage change over time is warranted.

Latent transition analysis (LTA), a longitudinal latent variable method that models discrete change and is particularly useful for stage-sequential models, was employed to estimate the stage membership and transition probabilities across time for the five health behaviors. Three studies were completed to determining intervention effects on stage of change membership and transitions in middle school adolescents.

The first study examined intervention effects on stage of change membership and transitions among adolescent physical activity, fruit and vegetable consumption, and TV viewing. The second study examined intervention effects on stage of change membership and transitions among adolescent smoking and alcohol use acquisition. Finally, the third study examined gender differences in stage of change membership and transitions among adolescent physical activity and fruit and vegetable consumption across intervention conditions.

Overall results indicate intervention differences in stage membership and transitions for the five behaviors, as well as differential effects for males and females in stage membership and transitions for physical activity and fruit and vegetable consumption across intervention condition.

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