Purrpose

If-then plans: a small but real difference

Short answer

If-then plans seem to make a small but real difference. In smoking reviews, quitting was 10.7% against 4.9%. For alcohol the effect is small and fades over time, and it was not seen for heavy-drinking nights. That is why we make no big promises.

What is an if-then plan?

"If X happens, I will do Y." For example: "If I want a cigarette after dinner, I will step onto the balcony and drink a glass of water." The decision is made beforehand rather than in the moment.

The numbers

  • Gollwitzer and Sheeran 2006: average effect d = 0.65 across 94 studies. This covers all kinds of goals, not substance use specifically.
  • Malaguti et al. 2020 (21 studies): alcohol g = 0.31 (0.21 to 0.42), smoking g = 0.31 (0.12 to 0.50).
  • McWilliams et al. 2019 (12 studies): quitting smoking OR 1.70 (1.32 to 2.20); quit rates 10.7% against 4.9%.
  • Cooke et al. 2023 (16 studies): weekly alcohol d+ = -0.14 (-0.24 to -0.03). Online delivery -0.04, not significant. Heavy episodic drinking -0.01, so no effect. The effect shrinks over time.

How to read this

The effect is small but consistent for smoking. For alcohol it is weaker and absent for heavy-drinking nights. No plan can honestly promise that you will succeed many times more often; that would not match the sources.

Write your own

  • Name the trigger concretely: "when I get home on Friday", "when I leave the meeting".
  • Make the action small and doable right away.
  • Three plans at most. Most people cannot recall more.
  • After a week, look at them and change the one that does not work.

Sources

  1. Gollwitzer & Sheeran 2006, Advances in Experimental Social Psychology 38
  2. Malaguti et al. 2020, Drug and Alcohol Dependence (PMID 32622228)
  3. Cooke et al. 2023, Drug and Alcohol Review (PMID 36173203)
  4. McWilliams et al. 2019, Health Psychology (PMID 31414843)

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