Motivation and emotion/Book/2015/Transtheoretical model of change and motivation

From Wikiversity
Jump to navigation Jump to search
Transtheoretical model of change and motivation:
What is the transtheoretical model of change and how can it be used to motivate people to change?

Overview[edit]

[Provide more detail]

What is the Transtheoretical Model of Change?[edit]

The transtheoretical model is based on ‘James Prochaska and Carlo DiClemete’s research on ‘self-change’, the stages of change model forms part of a broader conceptual framework which aims to eliminate unwanted or negative behaviours to improve healthy living’ (Prochaska and Velicer, 1997). It provides strategies, or processes of change[grammar?] to guide the individual through stages of change through actions and maintenance. ‘It has been widely used with eliminating smoking cessation, substance abuse, safe-sex, anorexia and more’ (Prochaska and Velicer, 1997).

This chapter will briefly introduce the Transtheorectical Model follow by discussing it's[grammar?] history, and the five stages of change, intervention and maintenance - including coping skills. Secondly[grammar?] it will compare this model to different models such as Social Learning Theory, Limitation Theory, The precaution Process Model and Cognitive Behavioural Therapy. [grammar?] and covering limitations, strengths and precautions of these theories. Finally conclude with the overall effectiveness of Transtheorectical Model of Change[grammar?].

History[edit]

The Transtheoretical Model ‘began in the 1970s as an effort to provide a coherent theoretical organization to delineate a predictable and overarching behaviour change process’ (Prochaska, 1979). It is named Transtheorectical Model because it incorporates key constructions from other theories. It describes stages of change, the process of change and ways to measure change. ‘Transtheorectical Model quickly became one of the widely used models of health behaviour due in part of its intuitive appeal. It departs substantially from many other individually oriented models of health behaviour by focusing more on changes in behaviour and less on cognitive variables believed to predict health behaviour and behaviour change’ (Glanz, Rimer and Viswanath, 2008).

Aimed Population[edit]

Glanz, Rimer and Viswanath (2008) found that ‘applying Transtheoretical Model to an entire at-risk population, like smokers, requires a systematic approach that begins with recruiting and retaining a high percentage of the eligible population. The study concluded that the issue may not be their ability to change their unwanted behaviour; but their access to quality change programs’. ‘The entire Transtheoretical Model, consist of stages of change, processes of change, self-efficacy, and decisional balance’ (Nigg and Courneya, 1998) It is arguably the ‘dominant model of health behaviour change, having received unprecedented research attention over the years, yet it has simultaneously attracted exceptional criticism at the stages of change’ (Armitage, 2010). On the other hand, ‘motivation for change has been construed as a fluctuating state of balance between the pros and cons of a behaviour’ (Janis and Mann, 1977). In another note, The Transtheoretical Model focuses on a ‘client’s readiness to change has led practitioners to recognize that motivation to change might be malleable, dynamic and nonlinear processes’ (Kennedy and Gregoire, 2009). According to Lippke and Plotnikoff (2009), ‘motivation to change their unwanted behaviour was higher in contemplation than in pre-contemplation but not higher in preparation that in contemplation. Self-efficacy was related to motivation in pre-contemplation, contemplation, preparation and maintenance stages but not as expected in the action stage. Therefore, response efficacy was correlated with motivation in the first three stages and not in the two active stages’.

Stages of Change[edit]

Prochaska (2008) believed ‘stage of change represents a term-related behaviour which can help participants make dimension for integrating principles and processes of change more effective decisions to decrease health risk behaviours from across leading theories of psychotherapy and behaviour and increase health enhancing behaviours’. The Transtheoretical Model ‘posits that health behaviour change involves progress through six stages of change. This includes precontemplation, contemplation, preparation, action, maintenance, and termination. Within these models, it is implied that different cognitive factors are important at different stages and that these subsequently become the foci in stage-matched interventions that are designed to transition people from one stage to the next’ (Sutton, 2007).

Generally, the ‘first three stages pre-contemplation, contemplation, preparation; are all pre-action stages and are conceptualised as temporal variations of an individual’s intention to carry out the behaviour. The remaining stages action, maintenance, termination; are post-action stages and are conceptualised in terms of the duration of the behaviour change’ (Behaviour works Australia). ‘Individual under this model are hypothesised to move through the stages in order, however, they may relapse and revert back to an earlier stage. Individual[grammar?] might also cycle through the stages several times before achieving long-term behaviour change' (Sutton, 2007).

Ten Processes of Change[edit]

Processes of Change 3

There are ‘ten processes of change that haven been identified for producing progress along with decisional balance, self-efficacy and temptations’ (Prochaska, Velicer, 1997). We can see the ten processes of change includes ‘consciousness raising, dramatic relief, self-re-evaluation, environmental re-evaluation, social liberation, self-liberation, helping relationships, counter conditioning, reinforcement management, and stimulus control' (Boston School of Public Health, 2013)[Rewrite to improve clarity]:

  • Consciousness Raising- Increasing awareness about the healthy behaviour.
  • Dramatic Relief- Emotional arousal about the health behaviour, whether positive or negative arousal.
  • Self-Reevaluation- Self-reappraisal to realize the healthy behaviour is part of who they want to be.
  • Environment Reevaluation- Social reappraisal to realize how their unhealthy behaviour affects others.
  • Social Liberation- Environmental opportunities that exist to show society is supportive of the healthy behaviour.
  • Self-Liberation- Commitment to change behaviour based on the belief that achievement of the healthy behaviour is possible.
  • Helping Relationships- Finding supportive relationships that encourage the desired change.
  • Counter-Conditioning- Substituting healthy behaviours and thoughts for unhealthy behaviours and thoughts.
  • Reinforcement Management- Rewarding the positive behaviour and reducing the rewards those come from negative behaviour.
  • Stimulus Control- Re-engineering the environment to have reminders and cues that support and encourage the healthy behaviour and remove those that encourage the unhealthy behaviour.

Six Stages of Change[edit]

Transtheorethecal model ‘recognises that different people are in different stages of readiness of change. It is important not to assume that people are ready for or want to make an immediate or permanent behaviour change. By identifying a person’s position in the change process, a worker or therapist can more appropriately match the intervention to the person’s stage of readiness. This would positively motivate the individual in making the effort to change’ (Prochaska and Velicer, 1997).

Stage One: Precontemplation =[edit]

Usually, ‘individuals in the pre-contemplation stage of change are not even thinking about changing their unwanted behaviour. They may not even see it as a problem, or they think that others who point out the problem are exaggerating. DiClemente referred these views as ‘the Four Rs’-reluctance, rebellion, resignation and rationalization. Reluctant individuals are those who through lack of knowledge or do not want to consider change. The impact of the problem has not become fully conscious. Rebellious individuals have a heavy investment in making their own decisions. They are resistant to being told what to do. Resigned individuals have given up hope about the possibility of change and seem overwhelmed by the problem. Many have made many attempts to quit or control their bad habit but failed. Rationalizing individuals have all the answer to the questions; they have plenty of reasons why that bad habit is not a problem, or why it is a problem for others but not for them’ (Gross,2006). ‘Encouraging re-evaluation of current behaviour and self-exploration would positively encourage an individual to consider the option of changing their behaviour’ (Virginia Tech).

Stage Two: Contemplation[edit]

Individuals in the ‘contemplation stage of change are willing to consider the possibility that they have a problem, and the possibility offers hope for change’ (Gross,2006). ‘Individuals in this stage tend to be ambivalent about change. In this stage, individuals are weighing the pros and cons of quitting or modifying their behaviour. Although they think about the negative aspects of their bad habit and the positives associated with giving up or reducing, they may doubt that the long-term benefits associated with quitting outweigh the short-term cost. The timeframe of this stage vary with individuals and can often never get through this stage. On the positive side, individuals are more open to receiving information about their bad habit, and more likely to actually see educational interventions and reflect on their own feelings and thoughts concerning their bad habit’ (Virginia Tech). ‘Validating the lack of readiness and conquering it with supporting examples, encouraging evaluation of pros and cons of behaviour change; and identify and promote new, positive outcome expectations would help individuals progress through this stage of change’ (Virginia Tech).

Stage Three: Preparation[edit]

‘The third stage is the preparation stage, where people have made a commitment to make a change. Individuals are motivated by gathering information through research on what they will need to do to change their behaviour. However, not all ambivalence has been resolved, but ambivalence no longer represents an insurmountable barrier to change. Most individuals in this stage will make a serious attempt to stop drinking in the near future. Individuals in this stage appear to be ready and committed to action’ (Gross, 2006). Every so often, ‘individuals skip this stage and try to move directly from contemplation into action and fall out or withdraw because they haven’t adequately researched or accepted what it is going to take to make this major lifestyle change. Ways of positively encourage individuals with this stage of change involves Identifying and assist in problem solving, helping individuals identify social support, verifying that individuals has underlying skills for behaviour change as well as encouraging small initial steps’ (Virgina Tech).

Stage Four: Action[edit]

The next stage is the action stage. ‘Individual advancing to this stage believe they have the ability to change their behaviour and are actively involved in taking steps to change their bad behaviour by considering a variety of different techniques’ (Virginia Tech). ‘This should be the shortest of all stages which can take around three to six months’ (Gross, 2006). ‘The amount of time individuals spend in action stage varies. This is a stage when people most depend on their own willpower. They are making overt efforts to quit or change the behaviour and are at greatest risk of relapse. Individuals in this stage also tend to be open to receiving help and are also likely to seek support from family and peers which plays a major role in the individual succeeding. Individuals are encourage focusing on reconstructing cues and social support, bolstering self-efficacy for dealing with obstacle and combat feelings of loss and reiterate long-term benefits’ (Virginia Tech).

Stage Five: Maintenance[edit]

The ‘maintenance stage involves being able to successfully avoid any temptations to return to the bad habit. Individuals in maintenance constantly reformulate the rules of their lives and are acquiring new skills to deal with life and avoid relapse. They are able to anticipate the situations in which a relapse could occur and prepare coping strategies in advance. This stage can last for 6 months to 5 years. This stage is often challenging to individuals as they continue to show commitment to sustaining their new behaviour. Individuals should plan for follow-up support, reinforce internal rewards as well as discuss coping with relapse (Virginia Tech).

Preventing Relapse[edit]

Coping skills and emotional support is important in maintenance stage, they play a major role in preventing relapse in an individual. One needs to learn to ask for help from an ‘experienced peer and use relation skills to reduce the intensity of the anxiety associated with cravings. Added to that one need to develop alternative activities, recognize ‘red flags’, avoid situations of known danger to maintaining new behaviour, find alternative ways of dealing with negative emotional states, rehearse responses to predictably difficult events, and use stress management techniques to create options when the pressure is intense. Always create reinforcement or self-rewarding in a way that does not undermine self-caring efforts have also shown to help in preventing relapse. Another important coping skill is to pay attention to diet and exercise to improve mood, reduce mood swings, and provide added strength to deal with stressful circumstances and secondary stress symptoms’ (Gross, 2006).

Individuals entering into ‘maintenance stage from relapse often demonstrate a stronger will power to permanently change. In the relapse stage, individuals are encouraged to evaluate the trigger for relapse and reassess motivation and barriers to plan a stronger coping strategy’ (Virginia Tech).

Stage Six: Termination[edit]

The final stage is the ‘termination stage which is the ultimate goal of the individual. At this stage, the individual no longer finds the bad habit a temptation or threat; they have complete confidence that they can cope without fear of relapse’ (Gross, 2006).

As individuals ‘progress through their own stages of change, it can be helpful to re-evaluate their progress in moving up and down through these stages’ (Gross, 2006).

Self-Efficacy[edit]

‘Social Learning Theory, which involves Pavlov’s classical conditioning, Skinner’s operant conditioning and Bandura, who proposed the extension of learning principles to include cognitive processes. It provided the framework from which Self-Efficacy Theory was developed. Social Learning Theory posits that behaviour is a result of interactions between both personal and environmental variables. According to Social learning theorists, behaviour is shaped through learning by environmental conditions. Perceived self-efficacy is viewed as the judgement of an individual regarding their capability in the organization and implementation of tasks in order that selected performances are achieved’ (Glanz, Rimer, and Viswanath, 2008). Self-efficacy, as defined by Bandura (1977), ‘is the perceived confidence in attaining and maintaining the predefined goals of change’ (Elena al., 2013). ‘Bandura‘s finding implied that performance accomplishments provide a source of self-efficacy expectancy information, which could be used by health care professionals in attempts to achieve health promoting behaviour change among individual. Self-efficacy judgement can also be responsible for determining the amount of effort an individual will expend and the length of time that such effort will endure in response to problems and adverse encounters. The stronger their perceived self-efficacy, the more robust and resolute their efforts will be; and vice versa’. (Holloway and Watson, 2001) Relating self-efficacy to Transtheoretical Model, would support how an individual maintain the changed behaviour[grammar?].

Decision Making[edit]

Clearly, decision-making is an important part of the Transtheoretical Model of Change. ‘The decision-making variable represents pros and cons of changing have been found to have systematic relationship across the stages of change for fifty health related behaviours. Individuals’ progress from a negative balance to a positive decisional balance is necessary but not sufficient for long-term behaviour change. The ten processes of change are helpful when applied differently at different stages of change. Individuals will do better if they have helping relationship available for support, particularly during times of stress and distress that can trigger relapse or discontinue. They need to condition new, healthier behaviour to counter temptations to relapse, such as walking, talking, or relaxing when stressed rather than relying on substances. The better the effort individuals make with such processes, the more likely they are to maintain long-term behaviour change’ (Prochaska, 2008).

Limitations and Strengths[edit]

Limitations[edit]

However in limitation-theory, ‘it ignores the social context in which change occurs. The lines between stages can be arbitrary with no set criteria of how to determine a person’s stage of change. The questionnaires that have been developed to assign a person to a stage of change are not always standardized or validated. There is no clear sense of how much time is needed for each stage, or how long a person can remain in a stage. The model assumes that individuals make coherent and logical plans in their decision-making process when this is not always true’ (Boston school of Public Health, 2013).

Every model has its limitation; ‘several literature reviews have not found support for stage-based interventions as an effective way to change some behaviour’ (Bridle and others, 2005). And ‘some limitation of the Transtheoretical model may results not from the model’s deficiencies but instead from how researchers operationalize stages of change and design intervention. Measures of stage can also be inaccurate, because people do not always correctly respond to question that would put them in one or another stage, and they can move among stages during the rime of study or intervention, and between measurement occasions’ (Glaz, Rimer, and Viswanath, 2008).

Another significant limitation of the Transtheoretical model involves its ‘classification of behaviour change into a series of six distinct stages as opposed to being understood as a continuous process’ (Bandura, 1997). Researchers proposed ‘potential value in the elimination of transtheoretical model time-frames, suggesting the integration of certain psychological variables, for example, self-efficacy; for the purpose of classifying individuals along a behaviour change continuum’ (Sutton, 2000).

In the Transtheoretical model, ‘people who are unaware generally would be classified as being in pre-contemplation. This puts those strongly opposed to the recommended behaviour and those who simply have not heard of it in the same category’ (Glanz, Rimer and Viswanath, 2008). An[grammar?] according to Green and others (1999), ‘these two group are actually quite different. Almost all young people who have not yet used substances like tobacco, alcohol, or other drugs are in the pre-contemplation stage for acquisition of such use, Therefore, it might be assumed that Transtheoretical Model does not apply very well to children and adolescents’.

Strengths[edit]

Putting aside the limitation, the major strength of the Transtheoretical Model is the ‘potential to tailor its constructs to appropriately fit an individual’s readiness to begin changing behaviour, making individually based interventions applicable at the population level. Different people are going to be at different levels of readiness’ (Prochaska and Velicer, 1997). Therefore, being able to do so would more successfully target and change an unwanted behaviour.

In addition to the potential of a population-based intervention approach, the Transtheoretical Model is ‘clear enough to be used by virtually any type of practitioner or researcher. The Transtheoretical Model has the capacity to combine clinical and public health intervention, which can maximize the success in health behaviour change’ (Nigg, al., 2011). Although Transtheoretical Model has demonstrated numerous positive results, the direct application of the ‘Transtheoretical Model and its measurement scales across health behaviours without preliminary scientific rigor is problematic’ (Joseph, Breslin & Skinner, 1999).

The Transtheoretical Model ‘places special emphasis on stages beyond action, including maintenance of the behaviour, which may be especially important for behaviour such as dietary change in which the steps required for losing weight may differ from those involve in keeping it off’ (Glanz, Rimer, and Viswanath, 2008). It also ‘used and validated in numerous studies related to tobacco consumption’ (Armitage, 2008), and have ‘proved it to be one of the most influential models in the study of behaviours related to quitting smoking’ (Segan, Borland & Greewood, 2004). However, different researchers (West, 2005) ‘have criticized the concept, the time frame, as well as the manner in which the different stages are evaluated’. A study by Morales, Pascual and Carmona (2010) found that ‘variables, opinions and attitudes from participants towards smoking strengthened the internal constancy towards to Transtheoretical model stages’.

Comparing With Other Models[edit]

Looking at the ‘The Precaution Adoption Process Model is a stage process focusing on the adoption of a new precaution or the abandonment of a risky behaviour that requires deliberate action. Although This model and Transtheoretical Model share much in common, focusing on stage approach to understanding and promoting long-term behaviour change; the Precaution Adoption Process Model differentiates between individual who are unaware of a given health threat, do not perceive themselves as personally susceptible to the given threat, and are deciding whether to adopt recommended protection behaviours’ (DiClemente, Crosby, & Kegler, 2002).

The ‘Transtheoretical model and Precaution Adoption Process Model explicitly include maintenance of behaviour changes, and the Health Belief Model and Theory of Planned Behaviour do not exclude it. However, conceptualization and prediction of maintenance of behaviour change may require refinement of construct and measures or other theories altogether’ (Rothman,2000). ‘The choice of suitable theory should begin with identifying the problem, goal, and units of practice’ (Sussman & Sussman, 2001), not with selecting a theoretical framework because it is intriguing, familiar or vogue. The gift of theory is that it provides the conceptual underpinning to well-crafted research and informed practice. ‘Transtheoretical model may be especially useful in developing smoking cessation interventions’ (Glanz, Rimer, & Viswanath, 2008).

Another model, ‘Health Belief Model attempts to predict health-related behaviour in terms of certain belief patterns. The model is used in explaining and predicting preventive health behaviour, as well as sick-role and illness behaviour’ (Hochbaum, Rosenstock, and Kegels, 1952).

However, ‘The Theory of Planned Behaviour, a modification of the theory of reasoned action, was based on the assumption that human beings are usually quite rational and make systematic use of the information available to them. According to the theory of planned behaviour, intention, devoid of unseen circumstances that limit individual control, will help predict future behaviour’ (Carmack &Lewis-Moss, 2009). And ‘Cognitive Behavioural Therapy is a problem-oriented strategy which focuses on current problems and finding solutions for individuals’ (National Library of Medicine, 2013).

Conclusion[edit]

In conclusion, Saywell and others (2003) may have found that ‘combining both Transtheoretical Model and Health Behaviour Model allowed greater tailoring of intervention’. However, compare[grammar?] to Cognitive Behavioural Therapy, ‘Stages of Change Model may have more permanent and long lasting effect on self-efficacy than Cognitive Behavioural Therapy’ (Jafari, Shahidi and Abedin, 2012). According to a study conducted by Jafari, Shahidi and Abedin (2012) on improving self-efficacy in Iranian substance dependent adolescents, it is ‘concluded that both Cognitive Behavioural Therapy and Stages of Change Model which include transtheoretical model, improves general and situational self-efficacy’. Moreover, ‘results shown that Cognitive Behavioural Therapy seems to be significantly more effective than Stages of Change Model in the short term but the opposite effect can be observed when self-efficacy is measured’ (Jafari, Shahidi and Abedin, 2012).

Reference[edit]

Armitage, C.H. (2008). A volitional help sheet to encourage smoking cessation: a randomized exploratory trial. Health Psychology 27 (5), 557-566.

Armitage, C.J. (2009). Is there utility in the transtheoretical model? British Journal of Health, 14(2), 195-210.

Australian Government (2004). The stages-of-change model. The Department of Health.

Bandura, A. (1977). Self-efficacy: Toward unifying theory of behavioural change. Psychology Review 84, 191-215.

Bandura, A. (1997). The anatomy of stages of change. American Journal of Health Promotion, 12(1), 8-10.

Behaviour Works Australia (N/A). Stage theories and behaviour change. Retrieved from http://www.behaviourworksaustralia.org/wp-content/uploads/2012/09/BWA_StageTheories.pdf

Boston University School of Public Health (2013). The Transtheoretical Model (Stages of Change). Behavioural Change Model.

Carmack, C.C., & Lewis-Moss, R.K. (2009). Examining the theory of planned behaviour applied to condom use: The effect-indicator vs. Causal-Indicator models. The Journal of Primary Prevention, 30(6), 659-676.

DiClemente, R.J., Crosby, R.A.,& Kegler, M.C. (2002). Emerging theories in health promotion practice and research: Strategies for improving public health. San Francisco: John Wiley & Sons.

Elena, C., Moscatiello, S., Bugianesi, E., Bellentani, S., Fracanzani, A.L., Calugi, S., Petta, S., Grave, R.D., & Marchesini, G. (2013). Stage of change and motivation to healthier lifestyle in non-alcoholic fatty liver disease. Journal of Hepatology, 58(4), 771-777.

Glanz, K., Rimer, B.K., & Viswanath, K. (2008). Transtheoretical theory. Health Behaviour and Health Education: Theory, Research and Practice. San Francisco: John Wiley & Sons.

Green, G.W., and others (1999). Dietary applications of the stages of change model. Journal of the American Dietetic Association, 99(6), 673-678. Gross, S.J. (2006). Relapse Prevention. Psych Central. Retrieved from http://psychcentral.com/lib/relapse-prevention/

Hochbaum, G., Kegel, S., & Rosenstock, I. (1952). Health belief model. United States Public Health Service.

Holloway, A., & Watson, H.E. (2002). Role of self-efficacy and behaviour change. International Journal of Nursing Practice, 8, 106-115.

Jafari, M., Shahidi, S., & Abedin, A. (2012). Comparing the effective of cognitive behavioural therapy and stages of change model on improving abstinence self-efficacy in Iranian substance dependent adolescents. Iranian Journal of Psychiatry and Behavioural Sciences, 6(2), 7-15.

Janis, I.L. & Mann, L. (1977). Decision making: A psychological analysis of conflict, choice and commitment. American Psychological Association. Joseph, J., Breslin, C., & Skinner, H., (1999). Critical perspective on the transtheoretical model and stages of change. Changing addictive behaviour: Bridging clinical and public health strategies. New York: Guilford Press.

Kennedy, K. & Gregoire, T.K. (2009). Theories of motication in addiction treatment: Testing the relationship of the treanstheoretical model of change and self-determination theory. Journal of Social Work Practice in the Addictions, (2), 163-183.

Lippke, S., & Plotnikoff, R.C. (2009). The protection motivation theory within the stages of the transtheoretical model- Stage-specific interplay of variables and prediction of exercise stage transitions. British Journal of Health Psychology, 14(2), 211-219.

Morales, Z., Pascual, L.M., & Jose, C. (2010). The validity of transtheoretical model through different psychological variables.Health & Addictions 10(2), 47-66.

National Library of Medicine (2013). Cognitive behavioural therapy. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072481/.

Nigg, C.R. & Courneya, K.S. (2004). Transtheoretical model: Examining adolescent exercise behaviour. Journal of Adolescent Health, 22(3), 214-224

Nigg, C.R., Geller, K.S., Motl, R.W., Horwarth, C.C., Wertin, K.K., & Dishman, R.K., (2011). A research agenda to examine the efficacy and relevance of the transtheoretical model for physical activity behaviour. Psychology Sport Exercise 12(1), 7-12.

Prochaska, J.O. (1979). System of psychotherapy: A transtheoretical analysis. Homewood, IL: Dorsey Press.

Prochaska, J.O. (2008). Decision making in the transtheoretical model of behaviour change. Medical Decision Making, 28, 845-849.

Prochaska, J. & Velicer, W.F. (1997).The transtheoretical model of health behaviour change. American Journal of Health Promotion, 19(1), 38-48. Rothman, A.J. (2000). Toward a theory-based analysis of behavioural maintenance. Health Psychology, 19, 64-69.

Saywell, R.M., & others. The cost effectiveness of 5 interventions to increase mammography adherence in managed care population. The American Journal of Managed Care, 9, 33-44.

Segan, C., Borland, R., & Greewood, K. (2004). What is the right thing at the right time? Interactions between stages and process of change among smokers who make an attempt to quit. Health Psychology, 23 (1), 86-93.

Sussman, S., & Sussman, A.N. (2001). Praxis in health behaviour program development. Handbook of Program Development for Health Behaviour Research and Practice.Thousand Oaks, California: Sage.

Sutton, S. (2000). Interpreting cross sectional data on stages of change. Psychology and Health,15, 163-171.

Sutton, S. (2007). Transtheoretical model of behaviour change. In S. Ayers, A. Baum, C. McManus, S. Newman, K. Wallston, J. Weinman & R.West (Eds.), Cambridge handbook of psychology, health and medicine, 2, 228-232.Leiden: Cambridge University Press.

Virginia Tech. The Stages of Change. Retrieved from http://www.cpe.vt.edu/gttc/presentations/8eStagesofChange.pdf

West, R. (2005). Time for a change: Putting de transtheoretical (stage of change) model to rest. Addiction, 100 (8), 1036-1039.