Theses and Dissertations Collection

Practitioners in the field of sport and performance psychology design performance enhancement interventions to improve performer outcomes while helping performers find enjoyment in the process. Performers involved in high-risk occupations are faced with excessive demands which pose a threat to quality of life and survivability and are uniquely positioned to benefit from sport and performance interventions. However, training time is valuable and limited, thus practitioners providing services within this domain face an increased demand to demonstrate intervention effectiveness. Practitioners must use measurement tools that are theoretically consistent with the intervention provided, and self-report scales are a valuable tool for measuring and demonstrating changes in psychological constructs of interest. Due to the dynamic performance contexts of high-risk occupations, approaches to performance enhancement should be mindful of the demands and limits of attention processing and must facilitate a performers ability to attend to the rapidly evolving environment without getting stuck on internal content. Acceptance and Commitment Therapy provides a framework with a goal to increase psychological flexibility; a model of behavioral processes which direct action toward desired outcomes while providing a means to relate to the myriad of internal content which is produced during performance. Appropriate scales are needed to convey the effectiveness of interventions modeled after this approach within this unique population. Therefore, the purpose of this research was to use responses from professionals in elite military occupations to assess the psychometric properties of two instruments designed to capture processes of psychological flexibility: (a) the Acceptance and Action Questionnaire-II (AAQ-II) 5-item, and (b) the Comprehensive Assessment of Acceptance and Commitment Therapy Process (CompACT) Scale. The AAQ-II 5-item assess an inversely related concept to psychological flexibility, psychological inflexibility; however, the 5-item version identified for use with military personnel in high-risk occupations had not been tested for invariance between relevant groups or across time. The AAQ-II 5-item demonstrated factorial validity across subgroups of interest and demonstrate partial measurement invariance across operation status, services rank, and a 4-week interval. The properties of the scale were adequate for assessing mean differences between groups and over time. There were no mean differences found between groups, however, the level of psychological inflexibility was higher at the end of four weeks. Due to the invariance properties of the AAQ-II, change identified could be attributed to true change in the construct. Evidence of factorial validity and measurement invariance of the AAQ-II make it a viable option for practitioners and researchers working with performers in high-risk occupations. Because there is debate about the appropriateness of continuing invariance analyses under assumptions of partial invariance and comparing means between groups of unequal sample size, the associated analyses were compared to fully invariant models and to groups of equal size to determine the impact on interpretation of results. Comparisons revealed that when noninvariant parameters were a small portion of the partially invariant models analyzed, they had limited impact on interpretation. In contrast, groups of equal sample sizes produced more accurate estimates. The CompACT was developed to address the limits in construct coverage and discriminate validity of the AAQ-II. Since initial development, researchers have identified several different factor structures for the CompACT. The most salient version has 15-items across three factors and is empirically and theoretically supported. However, this structure has yet to be confirmed within a high-risk occupation. Due to continued exploration of the factor structure, researchers have yet to conduct measurement invariance analyses. Confirmatory factor analyses were conducted and revealed that a 15-item model demonstrated acceptable fit. Additionally, multiple-group invariance analyses revealed that the CompACT-15 was invariant across service status. Means comparison between service status groups provided preliminary evidence that Department of Defense Civilians demonstrate lower acceptance of and ability to create space from their internal experiences than their Special Operations Forces military counterparts.