The effectiveness of acceptance and commitment therapy (ACT) on neurotic perfectionism and internalized self-criticism in neurotic perfectionist girls: A single-case experimental study

Introduction: Neurotic perfectionism has a variety of psychological consequences that should be considered in psychotherapy applications. Aim: The present study aimed to examine the effectiveness of acceptance and commitment therapy (ACT) on neurotic perfectionism and internalized self-criticism in neurotic perfectionist girls. Method: This study was conducted using a single-case quasi-experimental design with, concurrent multiple baseline. The research population consisted of neurotic perfectionist girls visiting counseling centers in Ahvaz in 2022. The participants were a sample of 5 girls selected using purposive sampling with a minimum cut-off score of 145 in the Neurotic Perfectionism Questionnaire (NPQ). The acceptance and commitment therapy (ACT) (Twohig & et al, 2021) was implemented in eleven 90-minute sessions. The participants completed the Neurotic Perfectionism Questionnaire (1994), and the Levels of Self-Criticism Scale (2004). The data were collected in three baseline, intervention, and three-month follow-up phases and analyzed using reliable change index (RCI), recovery percentage, and visual inspection. Results: The analysis of the recovery percentage showed the participants' neurotic perfectionism 17.67 and internalized self-criticism 19.73 improved in the intervention phase and their neurotic perfectionism 36.25 and internalized self-criticism 49.90 increased in the follow-up phase. Moreover, the reliability change index of both variables in the post-treatment and follow-up phases was significant (P=0.05). Conclusion: Considering the effectiveness of acceptance and commitment therapy in reducing neurotic perfectionism and internalized self-criticism by increasing psychological flexibility, this therapy can be used as an intervention method in neurotic perfectionist girl