The Transtheoretical Model (TTM) of behaviour change (also known as the Stages of Change Model) was originally developed as a model to understand why some people are more capable of changing their behaviour than others in the context of smoking cessation [18], and is now one of the most commonly used methods in health behaviour change modelling. It is a model that focuses on intentional change and individual decision making. 

TTM assumes that individuals don’t change their behaviour quickly or suddenly. Rather, the process of changing behaviour happens through a cyclical process, where the person moves through different stages depending on how ready they are to act on the specific health behaviour. 

According to TTM, behaviour change involves progressing through 5 sequential stages of motivation/readiness to change:

1. Precontemplation - in this stage, people are not seriously considering behaviour change in the foreseeable future (defined in TTM as the next 6 months). They may be aware about the need/possibility to change but be defensive or resistant to that change. 

2. Contemplation - People in this stage are aware that there is a problem and they are seriously considering behaviour change within the next 6 months, but they are not committed to act. They are more receptive to information and feedback but they may be unsure about the costs/benefits of changing. 

3. Preparation (or Determination) - People in this stage are ready for action and are seriously considering changing behaviour within the next month. They may have already attempted behaviour change (for example, by reducing the number of cigarettes they smoke).

4. Action - In this stage, individuals have made significant effort to change behaviour and they have achieved some behavioural targets (for example, not smoking for 48 hours). This stage can last for about 6 months before people progress to the last stage.

5. Maintenance - People in this stage have been able to sustain behaviour change for more than 6 months. They are confident that they will continue to maintain their health behaviour change.

According to TTM, we move through these stages in a forward linear fashion, although going back stages is possible (through, for example, relapse from the preparation back to the contemplation stage), and is often part of any behaviour change.

The TTM also identifies processes of change (or self-change strategies) that facilitate movement from stage to stage. Different processes are important to facilitate movement between different stages. Practitioners should leverage these cognitive, affective and evaluative strategies in their interventions to help move someone from one stage to the next. In the context of TTM, the main strategies for change between stages are:

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To move someone from the precontemplation to the contemplation stage, use consciousness raising to increase awareness about the problem and improve the accuracy of the information. Dramatic relief to generate emotional arousal about the health behaviour, whether positive or negative arousal, and environmental reevaluation to assess (cognitively and emotionally) how a personal behaviour may be impacting the person’s social environment. 

To move someone from a contemplation to a preparation stage, you can leverage self-reevaluation to help with the cognitive and affective assessment of the problem behaviour in relation to their self-image (for example, thinking how stopping smoking is part of being a responsible person)

To move from preparation to action, use self-liberation to help the person commit to the change based on the belief that achieving the healthy behaviour is possible. 

Finally, to facilitate the move between the action and the maintenance stages, use helping relationships to encourage supportive relationships that encourage the desired behaviour. Counter conditioning to encourage the adoption of healthier behaviours that will substitute the more problematic behaviours. Stimulus control to reduce the contextual cues associated with the unhealthy behaviours and increase the contextual cues associated with the desired behaviour. Reinforcement management by rewarding the person for engaging in the healthy behaviour and punishing them for not engaging in the desired behaviour and social liberation to notice environmental opportunities that exist to show that society is supportive of the healthy behaviour. 

Moving from any one stage to the next one is also influenced by 2 additional variables: decisional balance and self-efficacy. Decisional balance refers to the evaluation of the pros and cons of the specific health behaviour, so that if the person considers that there are more pros than cons, change will be more likely. Self-efficacy refers to a person’s beliefs about their ability to do the specific health behaviour in any given situation. High levels of self-efficacy make behaviour change more likely. On the contrary, low levels of self-efficacy increase the temptation to fall back to the unhealthy behaviour.

✅ Through the division into different stages and the associated change strategies, TTM allows practitioners to make individually-tailored interventions based on the individual’s (or the population’s) readiness to change, which should be more likely to be successful than ‘one size fits all’ approaches. 

✅ TTM takes into account individual differences and recognises that not everyone is equally ready for an intervention.

✅ TTM is a simple and clear enough model to be used by different types of practitioners or researchers.

❌ The lines between the different stages of change are blurry, with no set criteria on how to determine a person’s stage of change and arbitrary timings between stages. 

❌ TTM focuses on behaviours that can be addictive (smoking, alcohol abuse, drug abuse…). However, the model is based upon an entirely rational assumption of behaviour change, ignoring well known processes that operate outside of conscious awareness and that are crucial when considering addictive behaviours [19].

❌ TTM ignores the role of environmental and socioeconomic factors that can influence health behaviours.

❌ TTM has been applied mostly to health behaviour change, its application to other domains may be less straightforward.

❌ Several systematic reviews have concluded that there is limited evidence of the actual effectiveness of stage-based interventions for behaviour change [19 - 21]. A recent meta-analysis of randomised controlled trials found that TTM interventions were effective at changing physical activity (by addressing constructs such as self-efficacy and the different strategies for change) but the different stages of change made no difference. That is, selecting participants according to their supposed stage of change or basing the intervention on specific stages of change did not make any difference in the outcome [22].