Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

First Advisor

Wayne Velicer

Abstract

Currently, very little is known about the mechanisms involved in effective behavior change interventions. In order to determine which mechanisms of the model produced the behavior change, longitudinal mediation structural equation models are necessary. The current study aims to determine the processes that underlie behavior change mechanisms of a Transtheoretical Model (TTM) computer based physical activity intervention study administered to middle school students (N = 4,151) in the state of Rhode Island.

This study examined a subset of students (N = 534) who reported as physically active at baseline. For this study, the independent variables consist of behavioral processes; mediating variables consist of Pros, Cons and Self-efficacy, and the dependent variable measuring physical activity levels. Several longitudinal meditational models are used to determine which of the mechanisms of the TTM model produced a significant role in maintaining physical activity levels within this population of students.

The purpose of study one is to develop single longitudinal mediation models composed of all variations of the five independent variables (i.e., counterconditioning, dramatic relief, reinforcement management, stimulus control, self-reevaluation) and each of the three mediating variables (i.e., Pros, Cons, Self-efficacy), in combination with the dependent variable, physical activity. These models are necessary in order to determine which combinations of variables are making a significant impact on physical activity maintenance levels over time. The mediator Pros, was the best construct over time in combination with the independent variables, counterconditioning and stimulus control in the model.

The purpose of study two is to develop three way longitudinal mediation models composed of each of the five independent variables (i.e., counterconditioning, dramatic relief, reinforcement management, stimulus control, self-reevaluation) with all three of the mediator variables (i.e., Pros, Cons, Self-efficacy) with the dependent variable, physical activity. These models are necessary in order to determine if all three of the mediators presented together with an independent variable invokes a positive outcome in physical activity.

The purpose of study three is to examine the psychometric properties of the TTM in this middle school population of exercise maintainers. More specifically, group differences between race (White = 87%), ethnicity (Hispanics = 12%) and gender (Females = 43%) were examined within a three year longitudinal model. For this single longitudinal mediation model, Self-efficacy was as an IV, stimulus control the mediator and physical activity level was the dependent variable. This study is an investigative study to determine if the structure of the model is different among the groups, or Factorially Invariant, if the models are the same for each of the subgroups. Although good fit was determined for gender, none of the models were able to hold parametrically in the invariance test. This provides evidence for the conclusion for the groups to be treated the same within the model, as the groups do not differ.

Overall, one of the three mediators, Pros, demonstrated relevance to the physical activity intervention when administered to middle school students beginning the study as maintainers. Although two of the five processes of change, counter conditioning and stimulus control were more relevant to the model, not enough evidence is provided to delete the other three, reinforcement management, dramatic relief, and self-reevaluation, from the physical activity intervention. There was no evidence that providing cons in the model is beneficial to maintenance of physical activity. Therefore, future interventions may benefit from not including cons in TTM interventions created for middle school physical activity maintainers.

It is important to note that future studies such as ones created to examine how these results compare to different populations as well as studies designed to examine additional positive health behaviors are necessary.

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