Ecological Momentary Intervention for Reward in Anhedonia

"Participants in the experimental group complete a two-week ecological momentary intervention (EMI) consisting of three brief training units per day, each delivered via a smartphone. The exercises target different aspects of reward processing and are scheduled at specific times throughout the day.~The morning unit (to be completed between 10:00 and 12:00 a.m.) involves a positive mental imagery task guided by audio recording. Participants are guided to vividly imagine a future situation with the most pleasurable and meaningful outcome possible. They are encouraged to mentally activate all senses, thoughts, and emotions associated with this scenario.~The afternoon unit (to be completed between 3:00 and 5:00 p.m.) consists of a savoring exercise guided by audio recording. Participants recall a positive experience from the past and are instructed to re-experience and savor it mentally by focusing on its sensory details, emotional quality, and personal significance.~The evening unit (to be"

"Participants in the control group complete a two-week progressive muscle relaxation (PMR) program designed to match the reward training in both frequency and duration. The intervention consists of three daily units, each delivered via a smartphone app and guided by audio recordings.~The first and second units of each day consist of short audio-guided PMR sessions (approximately 5 minutes each). These exercises systematically guide participants through alternating tension and relaxation of different muscle groups to promote physical and mental relaxation.~The third unit of the day focuses on reflection. Participants are asked to evaluate their experiences with the relaxation exercises over the course of the day. They reflect on their ability to engage with the exercises, the perceived effects (e.g., feelings of relaxation), any difficulties they encountered, and strategies to enhance the effectiveness of relaxation in their daily life beyond the intervention."

All participants receive a psychoeducation session on the day before the respective intervention starts. In this session, a graduate-level study team member introduces the rationale behind the training (PMR or reward-training), and demonstrates each exercise. Participants also practice each task.