Perceptions of active and inactive prototypes are associated with objective measures of physical activity in adolescents

The benefits of physical activity are known, but the proportion of adolescents meeting daily activity guidelines remains low. The Theory of Planned Behaviour (TPB), which assumes reasoned intentions explain actions, is a useful framework for predicting activity, but it leaves variance unexplained. The Prototype Willingness Model (PWM) which builds on the TPB, proposes a reasoned action pathway and a second social reactive pathway in which perceptions of social images, or prototypes, explain actions via behavioural willingness. We explored whether variables in the PWM’s social reactive pathway explained variance in an objective measure of daily activity, over and above the reasoned action path. Participants aged 12–13 (n = 205) were invited to complete measures of constructs in the PWM and to wear an accelerometer for the next seven days. Overall, 126 students (65 males) participated. Reasoned intentions, attitudes and subjective norms explained 12.8% of variance in activity. Prototype perceptions and willingness explained an additional 13.1% of variance. Participants’ perceived similarity to active prototypes, and unfavourable perceptions of inactive prototypes, significantly predicted activity. There were no significant differences between sexes on psychological variables. These findings highlight the importance of targeting prototype perceptions to encourage physical activity in this age group.