Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Betsy Hoza

Second Advisor

Mike Rosen


A long-standing challenge for public health and safety is that motor vehicle crashes (MVCs) are the leading cause of death for U.S. teenagers, a population with disproportionately high crash involvement relative to other road users. Quantitative and qualitative research has identified distracted driving as a significant contributor to young drivers’ overrepresentation in MVCs. This study was designed in the context of this notable public health concern, and the primary goal was to examine psychological factors that are hypothesized, via the Theory of Planned Behavior, to underlie teenage drivers’ decisions to text-while-driving (TWD) with a focus on the influence of ADHD symptoms. The psychological factors of interest were attitudes toward TWD, perceptions of crash risk while TWD, self-perceptions of competence as a driver, and perceptions of task performance. The aims of this project were addressed through a program evaluation of an experiential driver training program designed to educate young novice drivers on the dangers associated with TWD. This program, Turn Off Texting (TOT), was designed and run by the Youth Safety Council of Vermont and the Vermont Department of Motor Vehicles, Safety and Education Unit. Participants included 1203 high school teenagers who participated in 42 TOT program demonstrations across Vermont. The first aim of this study was to examine the influence of ADHD symptoms on psychological factors and behavioral intentions while controlling for and examining the effects of age, gender, and driving experience. ADHD symptoms were associated with more favorable attitudes toward TWD, greater intentions to TWD in the future, and lesser intentions to intervene on a distracted driver in the future. Male gender and increased driving experience also tended to be associated with riskier attitudes, perceptions, and intentions. The second aim of this work was to examine if the psychological factors mediate the associations between ADHD symptoms and the two behavioral intention variables. Results from multiple mediation models showed that only attitudes toward TWD mediated the relations for both intentions to TWD and to intervene in the future. ADHD symptoms continued to have a direct effect on behavioral intentions even when accounting for the indirect effects of the psychological factors; these findings suggest a direct relation of ADHD symptoms and an indirect relation via attitudes. The third and final aim of this study was to investigate the influence of ADHD symptoms, as well as age, gender, and driving experience, on the rate of change in the psychological factors and behavioral intention variables over the course of the TOT program. Findings from two-level regression models showed that the TOT program generally was effective in its goal to produce safer views in regards to the psychological factors and intended behaviors. As hypothesized, ADHD symptoms were associated with less change toward safer attitudes, perceptions of crash risk, and both intentions to TWD and intentions to intervene in the future; the influences of male gender and increased driving experience were similar in their associations with less change toward safer attitudes, perceptions, and intentions. The findings from this study’s three aims have important implications for the development and continued evaluation of specialized driver training programs. Namely, attitudes toward TWD are a viable target for intervention given this factor’s direct and indirect (in the association of ADHD symptoms) effect on intended behavior. Increasing ADHD symptoms and male gender were associated with less change over the course of the program, which represent two areas for more specialized intervention and study.



Number of Pages

122 p.