Respiratory sinus arrhythmia predicts perceived therapy process of a group-based acceptance and commitment therapy intervention Author: William H O&#39;Brien1, Paul Goetz2, Aaron T O&#39;Brien3, Heather McCarren4, Eileen Delaney5 Affiliation: <sup>1</sup> Professor in the Department of Psychology, Bowling Green State University, Bowling Green, Ohio. <sup>2</sup> Assistant Professor in the Department of Cardiac Surgery and Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois. <sup>3</sup> Medical Student and Research Associate at the Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio. <sup>4</sup> Assistant Professor in the Department of Psychology, Xavier University, Cincinnati, Ohio. <sup>5</sup> Assistant Department head at the Naval Center for Combat and Operational Stress Control, San Diego, California. Conference/Journal: Bull Menninger Clin Date published: Winter 2021 Other: Volume ID: 85 , Issue ID: 1 , Pages: 9-22 , Special Notes: doi: 10.1521/bumc.2021.85.1.9. , Word Count: 155 Engagement in psychotherapy is partially contingent on present-moment focus, mindfulness, and emotion regulation skills. These skills can be linked to parasympathetic functioning with theoretical explanations provided by polyvagal and neurovisceral integration theories. The specific aims of this project were to evaluate relationships between a measure of parasympathetic functioning (respiratory sinus arrythmia [RSA]) and measures of client reports of engagement in an experiential and emotionally evocative group-based intervention. Twenty-one community residents received group-based acceptance and commitment therapy (ACT) for work stress. RSA was measured 1 week before the intervention. Client ratings of relationship support, task focus, and hindering experiences were assessed after each session. Results indicated that clients perceived the ACT intervention to be supportive, task-focused, and without significant therapy-hindering experiences. Higher levels of RSA were significantly associated with higher levels of relationship support. These results support predictions derived from the polyvagal and neurovisceral integration theories. Keywords: acceptance; mindfulness; respiratory sinus arrythmia; therapy process. PMID: 33750197 DOI: 10.1521/bumc.2021.85.1.9