Date of Award


Degree Type


Degree Name

Master of Science in Psychology


Clinical Psychology



First Advisor

James O. Prochaska


Research on the simultaneous treatment of multiple health risk behaviors has grown in recent years in the field of multiple health behavior change. Yet there is little research on how people change behaviors that are treated simultaneously. To help predict behavior change, and, thus, to prevent chronic illness on a population level, it is necessary to advance understanding of the patterns of behavior change. The present study examined participants with multiple health risk behaviors who have changed pairs of behaviors over time. Data were analyzed from four randomized controlled trials using Transtheoretical Model (TTM) tailored interventions and comparison groups (N = 1,277 weight management study; N = 9,461 cancer prevention study). Patterns of sequential (one behavior in a pair changed in a particular period, followed by the other) and simultaneous (both behaviors in a pair changed in the same time period and sustained that change) behavior change across four time points (baseline, 6, 12, and 24 months) were identified for each behavior pair. Ten different patterns of change were found and cohered into three distinct groupings of change: (1) overall simultaneous vs. sequential patterns, (2) simultaneous versus sequential patterns during the first phase of the study (first 12 months) and the second phase (12-24 months) of the study, and (3) simultaneous versus sequential patterns for those who recycled behaviors during the course of the study (over a 24 month time period). A series of chi-square analyses were conducted to examine differences between treatment and control group participants, participants with homogeneous and heterogeneous behaviors, and participants in different Stages of Change across each behavior pair within the three distinct groupings. Results are presented regarding the proportions of individuals who changed both behaviors in a pair sequentially or simultaneously, whether treatment and control groups followed different patterns of change, whether dissimilar behavior pairs (i.e., smoking, sun, diet) follow different patterns of change than similar behaviors (i.e., physical activity, diet, and emotional eating), and whether baseline Stage of Change impacts behavior change patterns. The findings provide a new window into the process of behavior change, illuminating a new way in which to understand the underlying mechanisms of behavior change. The discovery that the majority of behavior change is sequential rather than simultaneous advances the field of multiple health behavior change in a novel way; even when behaviors are treated simultaneously they are more likely to change sequentially.



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