Implementation intentions

method · origin: study · evidence: strong

In short

Wanting something (“I want to exercise”) doesn’t guarantee that you will actually do it. The psychologist Peter Gollwitzer proposed an extra step: you link, in advance, a concrete situation to a concrete action, in the format “if situation X arises, then I will do Y”. A plan like this is called an implementation intention. A 2006 meta-analysis (a study that gathers and combines the results of many studies), covering 94 independent comparisons (in effect, experiments), found a medium-to-large effect on goal attainment (Gollwitzer & Sheeran, 2006). A more recent meta-analysis, covering 642 independent comparisons, confirms that the method works and shows when it works best (Sheeran et al., 2024).

What it says

Goal versus plan. Gollwitzer distinguishes between two things:

The goal intention (“I intend to reach Z”), which says what you want.
The implementation intention (“if situation X arises, then I will do Y”), which says when, where and how you act.

The second does not replace the first. It is a plan built in service of it (Gollwitzer, 1999; Gollwitzer & Sheeran, 2006).

Why it might work. The central idea in Gollwitzer (1999) is that, through this kind of plan, the person “delegates” control of the action to a situation they have anticipated. When the situation arises, the behaviour starts more easily, almost automatically, without fresh deliberation. The 2006 meta-analysis found strong support for two proposed processes:

the situation specified in the plan becomes easier to notice and comes to mind more quickly;
the planned response becomes more automatic (Gollwitzer & Sheeran, 2006).

The goal says what you want; the plan says when and how you act. The last two boxes are the two mechanisms supported by the 2006 meta-analysis.

How big the effect is. Gollwitzer and Sheeran (2006) gathered 94 independent comparisons, from 63 reports, with 8,461 participants in total. The average effect on goal attainment was d = 0.65. The d index shows how large the difference is between the group that made a plan and the comparison group. By Cohen’s conventions, 0.2 means a small effect, 0.5 a medium one and 0.8 a large one, so 0.65 lies between medium and large. The 95% confidence interval (0.60–0.70) means the true value is probably between 0.60 and 0.70. The effect appeared:

for getting started on an action;
for shielding a goal from unwanted influences;
for disengaging from a course of action that isn’t working;
for conserving self-control resources for later.

The 2024 meta-analysis by Sheeran, Listrom and Gollwitzer covered 642 independent comparisons. Forming implementation intentions was effective for outcomes involving thoughts, emotions and behaviour, with effects between d = 0.27 and d = 0.66, depending on the type of outcome.

Example

An example cited by Gollwitzer (1999) comes from a study by Orbell, Hodgkins and Sheeran (1997). Women who had set out to do a breast self-examination in the following month were asked to write down where and when they would do it. Among participants who had a strong intention to do the self-examination, all of them (100%) did it if they had also formed an implementation intention. Without the extra plan, only 53% did it. The figures are taken from Gollwitzer (1999); we have not checked them in the original article.

How to apply it

The basic format is: “If [concrete situation], then [concrete action].” The situation should be something you will recognise at the right moment, such as a time, a place or a point in a routine. The action should be something you can start right away.

Examples (illustrative, built for this text):

Getting started on an action. Goal: to exercise three times a week. Plan: “If it’s Monday, Wednesday or Friday and I’ve closed my work laptop, then I’ll immediately put on my gear and go for a 20-minute run.”
Resisting a temptation. Goal: to stop opening social media while you work. Plan: “If I notice I’ve picked up my phone while working, then I’ll put it face down in the drawer and go back to the last sentence I was writing.”
Stopping a strategy that isn’t working. Goal: to finish a difficult project. Plan: “If I’ve been stuck on the same problem for more than 30 minutes, then I’ll stop and write a message to a colleague with the exact question.”

What the sources say about making the plan more effective:

Use the “if–then” format, not just “I’ll do X tomorrow”. Effects were larger when plans had a conditional format (Sheeran et al., 2024).
Start from a goal you really want. Effects were larger when participants were highly motivated to pursue the goal (Sheeran et al., 2024). Gollwitzer (1999) writes that implementation intentions need to be based on strong goal intentions.
Rehearse the plan and fix it in your mind. Effects were larger when plans were rehearsed (Sheeran et al., 2024). In a study cited by Gollwitzer and Sheeran (2006), participants who concentrated on the link between the situation and the action while writing their plan acted more often than those who only put their plan on a note as a reminder.
Commit to the plan. Gollwitzer (1999) describes studies in which stronger commitment to the plan led to larger effects.

Limits and nuances

It doesn’t work without a real goal. A plan does not create motivation that is missing. In the self-examination study, the effect appeared only in women who strongly intended to do it (Orbell et al., 1997, cited in Gollwitzer, 1999). When participants were told the goal no longer needed to be reached, the effect of the plan disappeared completely after 48 hours (Seehausen et al., 1994, cited in Gollwitzer, 1999).
The effect varies a lot from one study to another. Gollwitzer and Sheeran (2006) found large differences between studies (statistically significant heterogeneity). The figure of d = 0.65 is an average, not a promise for every situation. The 2024 meta-analysis also shows different effects for different types of outcome (0.27–0.66).
Most of the evidence comes from students. In the 2006 meta-analysis, 79 of the 94 comparisons were done with students. In the other samples examined (the general public, children and young people, people with physical illnesses), effects were of comparable size. In people with psychological problems they were even larger, but based on only three comparisons (Gollwitzer & Sheeran, 2006).
Rigidity. Gollwitzer (1999) acknowledges a possible cost: a fixed plan may reduce openness to suitable alternatives. He argues that this cost is not critical, because you can deliberately drop the plan. The rigidity at the moment the situation arises is, in his view, functional, because it shields the goal from distractions.
Individual differences are still an open question. Gollwitzer and Sheeran (2006) suggest, as a direction for research and not as a finding, that some people might benefit more from the method (for example those who procrastinate or are easily distracted). Also as a hypothesis, they say that for others, such as perfectionists, plans might be counterproductive.
The lead researchers are the same. Both meta-analyses have Gollwitzer, who proposed the concept, as a co-author. This does not invalidate the results, but it is worth knowing.

Sources

Peter M. Gollwitzer (1999). Implementation intentions: Strong effects of simple plans
Peter M. Gollwitzer, Paschal Sheeran (2006). Implementation Intentions and Goal Achievement: A Meta-analysis of Effects and Processes
Paschal Sheeran, Olivia Listrom, Peter M. Gollwitzer (2024). The when and how of planning: Meta-analysis of the scope and components of implementation intentions in 642 tests