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Imager – An mHealth mental imagery-based ecological momentary intervention targeting reward sensitivity: A randomized controlled trial

Introduction: Robust sensitivity to reward may help preserve positive emotions in the face of adversity and has been proposed as a key resilience factor. We describe the development, feasibility, and efficacy of an mHealth application, Imager, which targets reward sensitivity by training individuals to create mental images of future rewarding experiences.Methods: We conducted a randomized controlled trial with healthy student participants screened for low reward sensitivity. Fifty-one participants in the intervention group (IG) received an ecological momentary intervention (EMI) - Imager, including 10 ecological momentary assessment (EMA) prompts per day over 7 days, of which three were combined with an instruction to engage in a mental imagery training. This part encouraged participants to create a mental image of a rewarding event. Forty-four participants from the control group (CG) received 10 EMA prompts per day, without the option of performing mental imagery training.Results: Adherence to Imager was high; participants in the IG engaged in 88.4% of the planned EMAs and EMIs. Intervention group participants reported fewer mental health symptoms, mainly in depression (=−0.34, df=93, p=0.004) and less perceived stress (=−0.18, df=93, p=0.035) than CG participants. There were no significant changes in self-reported reward sensitivity in the IG.Conclusions: Mental imagery training of future rewarding experiences was accepted by participants and integrated into their everyday lives. Our results show positive effects of Imager on mental well-being, although direct target engagement – self-reported reward sensitivity – was not confirmed. Prospective studies are needed to investigate the psychological, physiological, behavioral and neural mechanisms underlying Imager’s effects based on additional data on other populations.