PRECIOUS: Digitally integrating motivational techniques to increase engagement with volitional processes for health behaviour change

Background: While behaviour change techniques (BCTs) derived from control theory can effectively change physical activity (PA) and dietary behaviours, the optimal methods for supporting engagement with these BCTs have yet to be established, particularly within mobile interventions. This study aimed to examine the acceptability and feasibility of a mobile app (PRECIOUS) that integrates motivational and volitional BCTs from self-determination theory, motivational interviewing and control theory, and includes tailoring and other features that attempt to optimize user engagement with the processes of changing PA and dietary behaviours.Methods: Twelve inactive adults participated in ‘think-aloud’ walkthroughs and used the PRECIOUS app for six weeks, wherein the effects of different combinations of BCTs upon user engagement and behaviour were examined. User interactions with the app were tracked automatically, and exit interviews with participants examined usability aspects, autonomy support, comprehension and perceptions of how and why intervention techniques did (not) work for them.Findings: Think-aloud walkthroughs revealed that the motivational interviewing BCTs in PRECIOUS elicited change talk from users, and consistent with self-determination theory, users appreciated the ability to pursue their own personally valued goals within PRECIOUS. While the app was found acceptable to users, some BCTs from motivational interviewing were viewed as difficult to operationalize within a smartphone application.Discussion: This study identified several limitations of a tailored smartphone app that integrates motivational interviewing and control theory based BCTs, and identified a number of ways that such a service could be improved to optimally maintain user engagement with control theory BCTs.