Sunday, May 27, 2012

How long does it take to form a new habit?

Habit is all about the relationship between repetition and automaticity. If a person starts a new behaviour and repeats it every day how long does it take for that behaviour to become automatic (habitual).
A person smokes marijuana everyday for a year. He then stops smoking marijuana = the new behaviour. How long will it take for the non smoking to become habitual or automatic. The answer is that there is not a linear relationship between repetition and automaticity. Instead the relationship results in an asymptotic curve as shown in this diagram.

Asymptotic curve of habit

The early days of the repetitions result in a quick increase in automaticity. After a time this slows and there is a plateau effect in the automaticity where more repetitions result in little increase in the automaticity.
A behaviour is generally regarded as fully habitual when a person reaches 95% of asymptote. A 100% is when further repetitions result in no more increase in automaticity and there is a complete plateau. Research suggests that the time to reach 95% of asymptote takes 66 days. There can however be considerable variation with a range from 18 to 254 days.

Woman smoking

Hence it can be said that for one to become a fully habitual non marijuana smoker will take 66 days. At that time the fully formed habit assists the person not to smoke marijuana again.


  1. Is this with regard to behaviour that we engage in each day? Or a particular number of times per day?

    The stuff on habits I've seen is usually stuff done several times a day like smoking.

  2. It mostly related to behaviour that was done once a day Evan,

    and it seems to show, as I say, that it takes about 2 months for a fully formed habit to develop.

    Of course as you know people have errors and forget and stuff like that so it is a general figure


  3. Fascinating series of posts. Thank-you.