Can Brief Text Messages Based on Control Theory Promote the Use of Bike Share Schemes?

BCTs have been used to promote many different behaviours including physical activity. Reviews show that the most effective techniques for promoting physical activity are self-monitoring, intention formation, feedback on performance, and goal setting. These techniques are also the core tenets of control theory, which suggests that setting, monitoring, and operating on goals are central to self-control.

To date, most of the intervention studies targeting psychological predictors of behaviour have used one-to-one communication by professionals, counselling, incentives etc. However, such methods may be difficult and costly to implement on a large scale. The proposed research therefore tests whether delivering these techniques via a convenient method (i.e. SMS text messages) is effective in promoting use of bike share schemes. We will also test whether the strength of participants' intentions to use bike share schemes moderates the effects of the intervention.

Participants will be randomly allocated into one of two groups (one experimental and control group). Participants in the control group will receive no messages. Participants in the intervention group will receive text messages prompting goal-setting (e.g. "How many times can you use a shared bike scheme over the next week? Set yourself a goal and challenge yourself!"), goal operating (e.g. "Make plans about when you could use a shared bike scheme, such as at a particular time or for a particular journey next week."), and self-monitoring (e.g. "Studies show that keeping track of progress can help people to achieve their goals. This is what the apps provided by the shared bike schemes can do for you!"). The messages will comprise of 160 characters at most and participants in the intervention group will receive three messages per week.

One month after taking the baseline survey, participants will be asked to fill in a follow-up survey which will ask them how many times they have used bike share schemes in total during the past month. This information is provided in the apps in "My Trips" section and participants will be asked to count the number of individual trips that they have taken since they completed the baseline survey. It is hypothesized that participants in the intervention group will use bike share schemes more frequently than those in the control group and that the intervention effect will be moderated by the strength of participants' initial intentions.

Mixed-measures (condition x time) ANOVA will be used to test for differences in shared bike use between the groups between baseline and follow-up. A moderation analysis will also be conducted to test whether the effect of the text messages on bike scheme use differs by intention strength.