Measuring psychological flexibility in adolescence

This thesis is submitted in partial fulfilment of the requirement for the degree of Doctorate of Clinical Psychology (DClinPsy). It is a portfolio thesis and as such consists of two separate papers. The systematic review and empirical paper have been prepared in accordance with the author guidelines for the target journal, the Journal of Contextual Behaviour Science. Psychological Flexibility Psychological Flexibility is a person’s ability to maintain or change behaviour according to their goals or values, with an awareness of impacts on their situation and complete openness to ongoing thoughts and feelings. The construct of PF has been hypothesised to be a principal aspect of psychological health and mental well-being. PF is understood to reflect three dyadic sub-processes, referred to as open, aware and active. PF is a common target of contemporary cognitive and behavioural interventions for promoting psychological health, but this is most explicitly stated within Acceptance and Commitment Therapy (ACT). Paper 1: Systematic Literature Review The Avoidance and Fusion Questionnaire – Youth (AFQ-Y) is a process measure, designed to assess psychological inflexibility in young people. The AFQY8 (short-form) is increasingly being adopted for research and clinical use, but its psychometric properties are unexamined. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) is a set of explicit guidelines for the selection of process / outcome measures in both research and clinical use. The guidelines provide robust methodological criteria for undertaking systematic reviews of process / outcome measures and whilst examining the psychometric properties they also critically evaluate the quality of the evidence. Through the application of COSMIN methodology, the review provides a benchmark for the level of confidence that can be held by researchers and clinicians when selecting to use the AFQ-Y8. Paper 2: Empirical Paper Given its purported centrality to psychological health, it is important that validated measures of PF are available; however, no comprehensive measure of PF exists for use with an adolescent population. In order to comprehensively measure PF, there is a requirement to reliably measure the three dyadic sub-processes. The Comprehensive assessment of ACT (CompACT) is a validated process measure currently used with adults but has not been validated with an adolescent population. The empirical paper evaluates the construct validity of the CompACT in order to understand whether it is understood by an adolescent population i.e., whether item content is clear, relevant, and interpreted/responded to in terms of targeted meaning. To achieve this, two studies were undertaken. In study 1, cognitive interviewing was conducted with 36 students (11-18yrs), with analysis showing that adolescents found problems with all 23-items, specifically in the understanding stage, and predominantly lexical problems. Subsequent analysis generated an alternative pool of items with age-specific adaptations. In study 2, consultation was undertaken with 11 international experts (in PF and/or using ACT with adolescents) using a web-based survey tool. The outcome informed selection of a final set of 23 alternative items with confirmed construct relevance for gauging PF in an adolescent population. The overall outcome of study 1 and 2 is a revised comprehensive measure of PF, which requires psychometric validation