An online intervention to increase physical activity: Self-regulatory possible selves and the moderating role of task self-efficacy

•We examined the effect of two possible selves interventions on physical activity.•We examined baseline self-efficacy as an intervention moderator.•Both interventions increased physical activity relative to control procedures.•Self-efficacy moderated the effect of both interventions on physical activity.

ObjectivesThe act of reflecting on physically active possible selves can increase physical activity (PA). According to theory, possible selves that include strategies for achieving them (self-regulatory possible selves) should have the greatest impact on behavior. Our aim was to examine whether forming a self-regulatory physically active possible self is more effective at increasing PA than forming a possible self that focuses only on the image of the possible self (self-enhancing possible self) or engaging in a control activity. Task self-efficacy was examined as a moderator.DesignAn online, randomized experimental study.MethodInsufficiently active adults (n = 244) completed task self-efficacy and PA measures before the intervention, and 4 and 8 weeks after.ResultsRepeated measures ANOVA revealed a 'time by condition' interaction whereby reported PA levels were higher for participants in the self-enhancing condition than for those in the control condition 4 weeks post-intervention. Reported PA levels were also higher for participants in the self-regulatory condition than those in the control condition at both follow-up time points. There was also a 'time by condition by self-efficacy' interaction, whereby participants in the self-enhancing condition reported more PA than controls at both follow-up points when they also reported high self-efficacy. Participants in the self-regulatory condition reported more physical activity than all other participants when they were also low on self-efficacy, but only at the four-week follow-up point.ConclusionThe findings extend the PA possible selves literature by suggesting that different types of possible selves interventions may work best depending on participants' task self-efficacy levels.