A goal says what you want to do. An implementation intention, Peter Gollwitzer’s term, says when and where you’ll do it: “If it’s 7am and I’m in the kitchen, then I’ll take two capsules with my coffee.” The plan hands control of the start to the situation, so the moment itself prompts the action.

The evidence

Gollwitzer and Paschal Sheeran pooled 94 independent tests in 2006 and found a medium-to-large effect on reaching goals (d = 0.65) Published. I’d treat that as an upper bound. Pooled studies from that era tend to run larger than what holds up in the field, which is why the field studies matter more.

The best known is a flu-shot trial by Katherine Milkman and colleagues at a large company. Every employee in the study got a letter with the times and places of free on-site clinics. Some letters also had a box asking the employee to write down the date they planned to go; others asked for the date and the time Published.

PublishedMilkman, Beshears, Choi, Laibson and Madrian, PNAS, 2011. The paper reports the control rate and each prompt’s difference from it (1.5 and 4.2 points); the rates shown add them. Bars start at zero.

A 4.2-point rise on 33.1% is a 12.7% relative increase, from a line of text on a letter that was going out anyway Derived. Note the detail: a date alone wasn’t enough. The more specific plan did the work.

Where plans stop working

Mariana Carrera and colleagues tried the same idea on something repeated. At a gym, 877 members were asked to pick the days and times they’d go over the next two weeks. Attendance didn’t rise; the authors call it “a tightly estimated null effect.” Their paper notes that the large field successes of planning prompts have been one-time actions: vaccinations, screenings, voting Published.

Use the plan for the first use. Use the setting for everything after it.

That’s the right split for a DTC brand. The first use is a one-time action, and a plan prompt fits it. The fortieth use is a routine, and routines come from repetition in a stable setting, which is the next two chapters.

How to ask

• On the order confirmation page, while intent is highest: “When will you first use it?” with one-tap answers (tomorrow morning, tomorrow evening, the day it arrives, pick a day) and “Where will you keep it?” with the likely places.
• Send the plan back to them, in their words, on the day they chose: “You said Tuesday morning, in the kitchen.” By email, or by text if they’ve agreed to texts.
• Hold out a random fifth of buyers who don’t see the prompt, and compare time to first use. The template is in Appendix B.

Do this

• Add the two-question plan prompt to your confirmation page this month, with the holdout. Read the result on time to first use after two cohorts, not on revenue.