Implementation intentions do not enhance all types of goals: The moderating role of goal difficulty

Three studies tested whether Gollwitzer and Brandstatter's (1997) failure to find an implementation effect for easy goals was due to a ceiling effect, to the moderating effect of previously formed habits, or to a moderating effect of earlier implementation intentions. The studies strongly indicated that easy goals did benefit from forming implementation intentions (i.e., specifying where or when one would perform the action). This suggests that Gollwitzer and Brandstatter's failure to find significant implementation effects for easy goals was due to a ceiling effect and not to other moderating effects. However, in the three experiments, we found no positive effect of implementation intentions for the enactment of goal-related behavior corresponding to a certain type of difficult goal. More specifically, when the focus was on the outcome of goal-directed action rather than on the goal-directed actions themselves, implementation intentions specifying when or in what conditions the relevant actions were to be performed did not enhance enactment. When the focus was on the goal-directed actions, we replicated the positive effect of forming implementation intentions. We argue that specifying when or where a goal-directed action should be enacted does not enhance enactment when the actor is not aware of the actions that are required to reach the goal. Possibly, implementation intentions specifying what one should do (rather than where or when) might be more helpful to enhance enactment rates of this type of goal.