Interoceptive Mechanisms of Body Image Disturbance in Anorexia Nervosa

Participants lay supine in one of two circular fiberglass pools that were custom-designed for research purposes. The floatation pools are 8 feet in diameter and contain 11 inches of reverse osmosis water saturated with \~1,800 pounds of Epsom salt (magnesium sulfate). This creates a dense saltwater solution with a specific gravity of \~1.26, allowing participants to effortlessly float on their back while the water hovers just above the ears. The temperature of the water and air is calibrated to approximate skin temperature (\~95.0 °F), helping to minimize the need for thermoregulation while reducing the boundary between air, body, and water. Clothing is usually not worn while floating since anything touching the body can generate somatosensory stimulation, detracting from the float experience. However, participants have the option to choose if they would prefer to float with a bathing suit or nude. During floatation-REST, visual, auditory, olfactory stimuli are minimized.

Two ACT principles, contact with the present moment and cognitive defusion were utilized in the development of the intervention. In the IFT condition, awareness and acceptance of bodily signals, thoughts, and emotions and being present with one's self (i.e., mindfulness focus is inward) are emphasized. All participants will engage in an introduction session. Followed by three IFT sessions. The experimental sessions are formatted the same for both conditions. Each begins with a clinician reviewing previous constructs and introducing a new skill. Then participants engage in their assigned condition intervention, followed by a debrief with a clinician. Practices in both conditions are matched as closely as possible for content. The mindful focus of IFT is internal toward thoughts, emotions, and body sensations. In the experimental sessions, participants will engage in a floatation-REST session while practicing acceptance and mindfulness-based skills presented to them.

Two acceptance and commitment therapy modules contact with the present moment and cognitive defusion were utilized in the development of the intervention. In the EFT condition, awareness and acceptance of thoughts and emotions and mindfulness of current experience are emphasized. The mindful focus of EFT is external, toward attending to experience as well as thoughts and emotions. During experimental sessions, participants will engage in a self-guided and computer-based practice of acceptance and mindfulness-based skills. These videos were created to ensure content was congruent with the material presented in the introduction sessions and represent skills that build from session to session.