Planning to break unwanted habits: Habit strength moderates implementation intention effects on behaviour change

TLDR

Implementation intention formation promotes goal attainment, yet its effectiveness when people have strong antagonistic habits remains largely unexplored. The study examined whether habit strength moderates the impact of implementation intentions on behavior change, specifically in a smoking cessation context. Experiment 1 induced habitual responses that impaired task performance after a switch, while Experiment 2 applied implementation intentions to smokers to assess how habit strength influenced outcomes. Implementation intentions mitigated habit‑related performance deficits and reduced smoking in participants with weak or moderate habits, but the effect was attenuated or absent in those with strong habits, indicating habit strength moderates effectiveness.

Abstract

Implementation intention formation promotes effective goal striving and goal attainment. However, little research has investigated whether implementation intentions promote behaviour change when people possess strong antagonistic habits. Experiment 1 developed relatively habitual responses that, after a task switch, had a detrimental impact on task performance. Forming an if-then plan reduced the negative impact of habit on performance. However, the effect of forming implementation intentions was smaller among participants who possessed strong habits as compared to participants who had weaker habits. Experiment 2 provided a field test of the role of habit strength in moderating the relationship between implementation intentions and behaviour in the context of smoking. Implementation intentions reduced smoking among participants with weak or moderate smoking habits, but not among participants with strong smoking habits. In summary, habit strength moderates the effectiveness of if-then plan formation in breaking unwanted habits.