Increasing the Effectiveness of a Physical Activity Smartphone Intervention With Positive Suggestions: Randomized Controlled Trial

Aleksandrina Skvortsova   ^{1, 2} , PhD ;   Talia Cohen Rodrigues   ² , MSc ;   David de Buisonjé   ² , MSc ;   Tobias Kowatsch   ^{3, 4} , PhD ;   Prabhakaran Santhanam   ³ , MSc ;   Dieuwke S Veldhuijzen   ² , PhD ;   Henriët van Middendorp   ² , PhD ;   Andrea Evers   ^{2, 5, 6} , PhD

¹ Department of Psychology, McGill University, Montreal, QC, Canada

² Health, Medical and Neuropsychology, Faculty of Social and Behavioural Sciences, Leiden, Netherlands

³ Centre for Digital Health Interventions, Department of Management, Technology, and Economics, ETH Zurich, Zurich, Switzerland

⁴ Centre for Digital Health Interventions, Institute of Technology Management, University of St.Gallen, St.Gallen, Switzerland

⁵ Department of Psychiatry, Leiden University Medical Center, Leiden, Netherlands

⁶ Medical Delta, Leiden University, Technical University Delft and Erasmus University, Leiden, Delft, Rotterdam, Netherlands