An if-then plan is one sentence that fixes when, where and how you'll start: "If it's Tuesday at 8:30 and I'm at the kitchen table, then I open the doc and type one line." Across 642 tests, people who made plans like this acted on their goals more than people who didn't, but only by a small amount.
Psychologists call it an implementation intention. Here is what the research does and doesn't say.
Where does the 642 come from?
A 2025 review pooled 642 tests of implementation intentions (Sheeran, Listrom and Gollwitzer, 2025). Those are tests, not 642 separate studies of procrastination. The review is about acting on goals in general. For people who put things off, there is a smaller study, below.
How big is the effect?
On what people actually did, the effect was d = 0.27. That number is the gap between people who planned and people who didn't, where 0.2 counts as small and 0.5 as medium. Across everything the review measured, it was d = 0.36.
Three things shrink it:
- Publication bias. Corrected for studies that only got published when they worked, the effect on behaviour falls to about 0.15.
- Lab versus life. Lab tests averaged 0.49. Field tests, where people were living their normal lives, averaged 0.27.
- Time. The effect was bigger right after the plan (0.48 within a week) than a month or more later (0.19 at one to six months). Only 12 tests looked past six months, and they happened to show 0.51, which is too few to lean on.
So an if-then plan helps a little, and it helps most soon after you make it. It is still one of the most tested ideas in behaviour science.
Does it work if you put things off?
One study of 152 students found that those who made if-then plans had about 8 times the odds of keeping an appointment, with no sign it worked less well for chronic procrastinators (Owens, Bowman and Dill, 2008).
A field study asked employees to write down a date and a time for a flu shot. Vaccination went up by 4.2 percentage points. A date alone gave 1.5, which was not statistically significant (Milkman and others, 2011). One field study is one field study, though: the 2025 review found no reliable effect on vaccination overall.
What makes a plan better?
These come from comparing different studies, not from experiments, so read them as hints, not rules. In the review:
- Plans that named a time and a place scored d = 0.46. Plans that named only a time scored 0.25.
- The if-then format scored 0.43. A plain schedule scored 0.29.
- Rehearsing the plan at least once scored 0.45, against 0.33.
- Adding how long and how to do it scored lower (0.24), and so did making three to five plans instead of one (one plan: 0.41).
What about the things that get in the way?
Plans cued by an event such as a setback scored between 0.31 and 0.44. "If I get stuck, then I write down the question I'm stuck on and stop."
Plans made at the end of a task, about the next start, scored between 0.49 and 0.64. So before you stop for the day, write down the first step of next time.
How do you write yours?
- The when and where. "Tuesday, 8:30pm, kitchen table."
- The first step. Small enough that you don't have to decide anything. This part is reasoning. Putting things off goes with a task feeling unpleasant and with doubting you can do it (Steel, 2007), and a small first step goes after both. But those are correlations, and we found no trial of a tiny first session against a normal one.
- One for the obstacle. "If I get stuck, then I write the question down and stop."
Where does Omodo fit?
Omodo writes these for you. It turns the thing you keep meaning to do into a plan of short sessions, starting from where you are, and every session has a day, a time, a place and a first step. It reminds you before each one, and the first session is 20 minutes at most. You can start free; the current price is on the pricing page. Omodo has not measured its own results yet. The research above is why it is built this way, not a promise about what it will do for you.