Reinforcing implementation intentions with imagery increases physical activity habit strength and behaviour.

OBJECTIVES

Habits may enhance the maintenance of physical activity. The aim of this study is to examine if reinforcing implementation intentions increases habit strength and thus physical activity.

DESIGN

Participants (N = 186) were randomized into one of three intervention conditions (imagery vs. implementation intentions vs. combined; implementation intentions and imagery) and a control condition.

METHODS

Participants were instructed to engage in a physical activity that they would like to start doing, or do more of, over a four-week period. Participants completed measures of physical activity, habit strength, and imagery use (imagery and combined conditions only) pre-intervention, weekly during the intervention, post-intervention, and a 12-week follow-up.

RESULTS

Habit strength increased at week three (p < .001) for those in the combined condition, which was maintained through post-intervention and increased at follow-up (Ps > .05). In the imagery condition, habit strength increased at post-intervention (p = .003) and was maintained at follow-up. Physical activity increased for the combined condition from week two (p < .001) of the intervention, continuing to increase at weeks three (p = .003) and four (p < .001).

CONCLUSIONS

Imagery may be an effective intervention to support habit formation. Reinforcing implementation intentions with mental imagery may support habit formation for physical activity behaviour.