Gunther Meinlschmidt*, University of Basel; Ruhr-University Bochum, Basel; Bochum, Switzerland Esther Stalujanis, University of Basel, Basel, Switzerland Joel Neufeld, University of Basel, Basel, Switzerland Marion Tegethoff, University of Basel, Basel, Switzerland Track: Research Presentation Topic: Mobile & Tablet Health Applications Presentation Type: Rapid-Fire Presentation Submission Type: Single Presentation Last modified: 2014-05-16

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Background
The increasing availability of smartphones has provided new opportunities to deliver mental health care. However, the processes underlying changes following smartphone-based interventions are largely unknown. Notably, with regard to conventional interventions, the placebo effect is an important factor leading to intervention-related changes. Thereby, patient's expectancy of the effects induced by the intervention seems to be a crucial underlying process.
To the best of our knowledge, the placebo effect has not yet been scrutinized for smartphone-based interventions. However, as new mobile technologies will play an important role to meet future needs in mental health services, it is important to investigate if the same placebo-related mechanisms apply as in conventional face-to-face psychotherapy.

Objective
To investigate the placebo effect in a smartphone-based training, ostensibly designed to improve mood and perceived stress by daily exposure to color and mock sound.

Methods
Study subjects will be invited to participate in smartphone-based training sessions twice a day for 14 consecutive days. Each training session will consist of several parts: Part 1 (‘Pre-training’): Subjects take a portrait photo; Part 2 (‘Pre-assessment’): Subjects are required to provide information on current mood and stress-levels; Part 3 (‘Placebo-exposure’): This part consists of one of two modalities: During one of the daily trainings, subjects will be exposed to a visual stimulus (green light), during the other daily training, subjects will be exposed to a mock acoustic stimulus – being told that a high-pitched sound, above perception threshold, is present (no sound provided in real) (for details, see below). Part 4 (‘Post-training’): Subjects are asked again to take a portrait photo, followed by a message provided to the subjects (for details, see below). Subjects will be randomized to 4 conditions: Subjects in condition 1 will receive an instruction aiming at inducing prospective expectancy that the visual and acoustic exposure generally reduces stress and negative emotions; Subjects in condition 2 will receive feedback aiming at inducing retrospective expectancy that the visual and acoustic exposure reduced stress and negative emotions in their individual case; Subjects in condition 3 will receive instructions/feedback aiming at inducing both, prospective general expectancy and retrospective individual expectancy; Subjects in condition 4 will receive no instructions/feedback that aim at inducing any expectancy (control group). Prospective general expectancy will be induced in condition 1 and 3 by instructing subjects that watching the color and listening to the sound (during part 3) commonly reduces stress and improves mood. Retrospective individual expectancy will be induced in condition 2 and 3 by providing mock feedback (during part 4) that – based on the comparison of facial emotions assessed with the portrait photos (not assessed in real) – the light/sound exposure reduced stress and improved mood in their individual case. On day 1, 7, and 14 we will assess the subject's expectations regarding intervention effects in order to estimate whether these change during the course of the study.
To estimate placebo effects, we will compare exposure-related changes in mood and stress levels between conditions, using generalized linear models.

Results
Research in Progress

Conclusion
Research in Progress