How can the impact of implementation intentions as a behaviour change intervention be improved?

Interventions requesting individuals to form implementation intentions, specific plans regarding how and when to enact behaviour, have been shown to be effective in changing a wide range of health, social, and organisational behaviours. A small proportion of studies have sought to identify, within full-factorial designs, under what circumstances and for whom implementation intention-based interventions are most effective. This review covers this issue. A number of potential moderators of the effects of implementation intentions on behaviour were identified (intentions, motivation type, collaboration, plan reminders, goal type, plan type, conscientiousness, perfectionism, procrastination, stress). Of these, the strength of one's intentions have been tested, and supported, most often as a moderator of implementation intention effects. For some of these moderators (e.g., conscientiousness, goal difficulty) the results were contradictory but for others the results were more consistent (e.g., motivation type, plan reminders). Additional moderators might be identified by comparing effects of implementation intentions across studies. Published by Elsevier Masson SAS.