Published on in Vol 7 , No 2 (2019) :February
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/11636, first published
.

1 Department of Psychology, University of Milano-Bicocca, Milano, IT
2 Department of Clinical, Educational & Health Psychology, University College London, London, GB
3 Institute of Digital Health, University College London, London, GB