In 1960, plastic surgeon Maxwell Maltz published a book that would popularize the misconception that it only takes 21 days to change behavior and form new habits.
Dr. Maltz based this number on his observations, when he found that his patients needed 21 days to adjust to their new faces.
Scientists from Caltech, the University of Chicago and the University of Pennsylvania have questioned Dr. Mattles’ statements, Science Alert reports.
They used data from over 30,000 fitness enthusiasts; More than 12 million sports sessions have been scanned in this way.
They also used data from more than 3,000 hospital workers who, cumulatively, have washed their hands more than 40 million times.
Their results have been published in an article in the journal PNAS.
Using machine learning tools to analyze when people’s behaviors become predictable — and therefore habitual — the researchers found that some habits take longer to form than others.
For example, it takes an average of six months to get used to playing sports.
“Contrary to popular belief that there is a ‘magic number’ of days to form a habit, we found that it takes months to get into the habit of going to a workout, but weeks to get used to hospital hand washing,” wrote the team of behavioral scientists led by Colin Kammerer of Caltech.
