This research was conducted by Phillippa Lally when she held a Medical Research Council PhD studentship and has been written up during an Economic and Social Research Council postdoctoral fellowship.
How are habits formed: Modelling habit formation in the real world†
Version of Record online: 16 JUL 2009
Copyright © 2009 John Wiley & Sons, Ltd.
European Journal of Social Psychology
Volume 40, Issue 6, pages 998–1009, October 2010
How to Cite
Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W. and Wardle, J. (2010), How are habits formed: Modelling habit formation in the real world. Eur. J. Soc. Psychol., 40: 998–1009. doi: 10.1002/ejsp.674
- Issue online: 15 SEP 2010
- Version of Record online: 16 JUL 2009
- Manuscript Accepted: 12 JUN 2009
- Manuscript Received: 5 JUN 2009
To investigate the process of habit formation in everyday life, 96 volunteers chose an eating, drinking or activity behaviour to carry out daily in the same context (for example ‘after breakfast’) for 12 weeks. They completed the self-report habit index (SRHI) each day and recorded whether they carried out the behaviour. The majority (82) of participants provided sufficient data for analysis, and increases in automaticity (calculated with a sub-set of SRHI items) were examined over the study period. Nonlinear regressions fitted an asymptotic curve to each individual's automaticity scores over the 84 days. The model fitted for 62 individuals, of whom 39 showed a good fit. Performing the behaviour more consistently was associated with better model fit. The time it took participants to reach 95% of their asymptote of automaticity ranged from 18 to 254 days; indicating considerable variation in how long it takes people to reach their limit of automaticity and highlighting that it can take a very long time. Missing one opportunity to perform the behaviour did not materially affect the habit formation process. With repetition of a behaviour in a consistent context, automaticity increases following an asymptotic curve which can be modelled at the individual level. Copyright © 2009 John Wiley & Sons, Ltd.