How long does it take to form a habit? A multi-center replication
Sanne de Wit 
Maik Bieleke
Paul Fletcher
Annette Horstmann
Julia Schüler
Lotte P. Brinkhof
Lukas J. Gunschera
Jaap Murre
How long does it take to form a habit? This question will be addressed by an innovative study by Lally et al. (2010), in which they tracked the subjective automaticity of a novel, daily (eating or exercise-related) routine, using the Self-Report Habit Index. They showed that the gradual automatization of a novel routine is best described by an asymptotic curve, and that it takes (a median of) 66 days to reach the asymptotic ‘habit plateau’, with a range of 18 to 254 days (based on statistical extrapolation). However, these findings were based on a small sample of 39 participants, and this influential study has not been replicated yet. Therefore, the aim of the present study is to conduct a near-exact, multi-centre replication at four different locations. We aim to recruit 800 participants to increase reliability.