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The Transtheoretical Model of behaviour change, known to many as the Stages of Change (SOC) model, states that with regard to chronic behaviour patterns such as smoking, individuals can be characterized as belonging to one of five or six ‘stages’ (Prochaska et al. 1985; Prochaska Prochaska ‘contemplation’ involves an individual planning to stop between 31 days and 6 months, or less than 31 days if they have not tried to quit for 24 hours in the past year; ‘preparation’ involves the individual having tried to stop for 24 hours in the past year and planning to stop within 30 days (it has been accepted by the proponents of the model that having tried to stop should perhaps be dropped from this stage definition); ‘action’ involves the individual having stopped for between 0 and 6 months; ‘maintenance’ involves the individual having stopped for more than 6 months. In some versions of the model there is also a ‘termination’ stage in which the individual has permanently adopted the new behaviour pattern. The model further proposes that individuals progress through stages sequentially but usually revert to prior stages before achieving maintenance and then termination (Prochaska Bunton et al. 2000; Whitelaw et al. 2000; Sutton 2001; Etter Littell Mook 1996; Salamone et al. 2003). Much of the problem of behaviour change arises from the fact that unhealthy habit patterns become entrenched and semi-automated through repeated reward and punishment (Robinson Herzog et al. 1999; Abrams et al. 2000). Strong claims have been made for the model (Prochaska Littell and people who try to do something are more likely to succeed than those who do not. Surprisingly, the proponents of the model appear not to report findings showing that the model is better at predicting behaviour than a simple question such as ‘Do you have any plans to try to . . . ?’ or even ‘Do you want to . . . ?’. However, where others have made the comparison (e.g. SOC versus a simple contemplation latter that preceded it), little difference has been found (Abrams et al. 2000), or a simple rating of desire has been found to be better (Pisinger et al. 2005). There have also been problems in the reliability of the assignment to categorical stages, as one might expect given that these are designated arbitrarily (Hodgins 2001). One might imagine that a scientific model would need to show an improvement at least on this kind of simple assessment. Proponents of the model may point to the fact that at least it has drawn attention to the fact that many people are not ready for interventions and progress can be made by moving them in the direction of changing their behaviour. However, in the years that the model has been in use there appears to be no convincing evidence that moving an individual closer to action actually results in a sustained change in behaviour at a later date. In fact, the history of behaviour change research is littered with studies that have succeeded in changing attitudes without accompanying changes in behaviour. Where interventions have been developed that are based on the model these have not proved more effective than interventions which are based on traditional concepts. A recent review comparing stop smoking interventions designed using the SOC approach with non-tailored treatments found no benefit for those based on the model (Riemsma et al. 2003). Another review of the effects of applying the model to primary care behaviour change interventions has similarly found no evidence for a benefit (van Sluijs et al. 2004) and nor has there been found to be a benefit of applying the model in promotion of physical activity (Adams b), but the SOC model can be taken as giving permission to those attempting to promote behaviour change to give weak interventions or no intervention to ‘precontemplators’. This approach fails to take account of the strong situational determinants of behaviour. Behaviour change can arise from a response to a trigger even in apparently unmotivated individuals. It is common in the case of psychological theories for which there is accumulating evidence that they are not proving helpful, to argue that better measurement is needed or that the theory has not been applied properly. This particular model is no exception (e.g. DiClemente et al. 2004). In the end one is often forced to acceptance that fundamental precepts of the theory are misplaced and arguably that is the case here. A better model of behaviour change is clearly needed. There are of course many other decision-making models, such as the Health Belief Model (Garcia & Mann 2003) and the Theory of Planned Behaviour (Garcia & Mann 2003). What is needed is one that operates at the same level of generality as the SOC model and encompasses decision-making processes and motivational processes that are not necessarily accessible to conscious awareness. The model needs to take account of the fact that the behaviours concerned reflect the moment-to-moment balance of motives. At a given time an individual may ‘want’ to do one thing (e.g. smoke a cigarette) but feel they ‘ought’ to do something else (e.g. not smoke it)—but these feelings and beliefs are not present most of the time—they arise under specific circumstances. A model of change needs to describe what these circumstances are and how an individual's desires and values are shaped and changed. The model needs to consider the difference between desire and value attaching to a specific behaviour (smoking a cigarette) vs. a label (being a smoker). Lasting behaviour change relies on the balance of motivational forces regarding the specific behaviour consistently favouring the alternative whenever the opportunity to engage in it arises. The model of change needs to describe and explain how this occurs. It is apparent that self-labelling plays an important role in generating this consistency (Kearney & O’Sullivan 2003). An individual who is committed to being a ‘non-smoker’ is motivated to exercise restraint when temptation to smoke arises. A ‘state of change’ model is needed which provides a coherent account of the balance of motivational forces that operate on habitual behaviours, and how these need to change for a different pattern of behaviour to emerge. It needs to consider ‘state’, not as an outcome but as a measurable characteristic (possibly a self-label) that can help to stabilize a new behaviour pattern. It is worth noting, finally, that many practitioners already regard the SOC model as a state of change model in that they informally consider it to represent the state of readiness to change. In the course of researching this editorial, I have been forced to think about the kind of comprehensive model that is required and have proposed a draft of a model (West in press). It remains to be seen how far this can form a more scientifically sound basis for analysis of behaviour change. In the meantime, when it comes to intervening to promote behaviour change, health professionals should adopt the approach that worked well in Russell et al.'s seminal study of GP advice (Russell et al. 1979) and has been found to be effective more recently as well (Pisinger et al. 2005), which is to encourage change in, and offer help to, all-comers (except those who are clearly resistant). They should do this respectfully but firmly and with the offer of support and assistance. When it comes to assessing motivation to change, it would be better to revert to simple questions about desire to change that were in place before the SOC model was developed.
Robert West (Wed,) studied this question.