West, R., The transtheoretical model of behavior change and the scientific method. Addiction, 2006. 101(6): p. 774-8.
West, R., Problems with the Transtheoretical Model of Behaviour Change, PPT Lecture, University College London, January 2009
The Transtheoretical Model (i.e. The Stages of Change Model) is an outdated and scientifically frail approach. According to this theory, behavior change involves moving forward through the stages (Pre-contemplation, Contemplation, Preparation) up to the Action stage. Reversion to a previous stage is common, but with repeated attempts the Maintenance stay may be achieved. The essential premise is that interventions to promote behavior change should match techniques to the current stage of the individual to move them to the next stage. In general, evidence claimed to support the model is the following: 1) Individuals further along the stages towards maintenance are more likely to have undergone behavior change at follow-up 2) Individuals in different stages report having used different behavior change processes to get there 3) Stage-matched interventions have proved successful in promoting behavior change. However, “Stages” as they are presented do not exist in any meaningful sense. Whereas individuals clearly differ in desire to change and this is quite stable over time, intentions are fluid. For example, transition through pre-action stages is not the norm or necessary for successful change. Many (in the case of smoking cessation, at least 50%) change attempts involve no prior planning and such attempts are at least as likely to succeed as those that involve pre-planning. The change process is much more dynamic, heterogeneous and stimulus-driven than is implied by the model. Attempts at change are made, suspended, abandoned, and re-instated in a much more dynamic manner than the model implies; the nature of the intention regarding change is also variable (e.g. ‘cutting down on smoking’, ‘stopping’, ‘only smoking in the evening etc.) The emphasis on processes of change is on conscious decision making factors and the model underplays key determinants of success at change such as habit and addiction. Moreover, studies have repeatedly found that a simple ‘addiction’ model is more successful at predicting successful change than ‘stages of change’. Pre-action stage of change has not been found to be better than simple ratings of desire to change in predicting change at follow-up. The Inter 99 study appears to be the only study thus far comparing Stage of Change and simple rating of desire for change in predicting change and finds desire to be at least as good. Therefore, TTM-based interventions have not been found to be more successful than other methods at promoting behavior change. Systematic reviews conducted by third parties have not found TTM-based interventions to be more effective than other methods when it comes to actual behavior change, despite some by proponents of TTM have interpreting their results as showing a positive benefit of TTM approaches.