Stages
Stephen Sutton
University of Cambridge

Stage theories assume that behavior change involves movement through a sequence of discrete stages, that different variables influence different stage transitions, and that effective interventions need to be matched to stage (Sutton, 2005 xClose
Sutton, S. (2005). Stage theories of health behaviour. In M. Conner & P. Norman (Eds.), Predicting health behaviour: Research and practice with social cognition models (2nd ed., pp. 223-275). Maidenhead, England: Open University Press.; Weinstein, Rothman & Sutton, 1998 xClose
Weinstein, N. D., Rothman, A. J., & Sutton, S. R. (1998). Stage theories of health behavior: Conceptual and methodological issues. Health Psychology, 17, 290-299.). Stage is the central construct in the transtheoretical model (TTM; Prochaska & Velicer, 1997 xClose
Prochaska, J. O., & Velicer, W. F. (1997). The transtheoretical model of health behavior change. American Journal of Health Promotion, 12, 38-48.), the precaution adoption process model (PAPM; Weinstein, 1988 xClose
Weinstein, N. D. (1988). The precaution adoption process. Health Psychology, 7, 355-386.; Weinstein & Sandman, 1992 xClose
Weinstein, N. D., & Sandman, P. M. (1992). A model of the precaution adoption process: Evidence from home radon testing. Health Psychology, 11, 170-180.), the stage version of the health action process approach (HAPA; Schwarzer, 2008 xClose
Schwarzer, R. (2008). Modeling health behavior change: How to predict and modify the adoption and maintenance of health behaviors. Applied Psychology, 57, 1-29.), the health behavior goal model (Maes & Gebhardt, 2000 xClose
Maes, S., & Gebhardt, W. (2000). Self-regulation and health behavior: The health behavior goal model. In M. Boekaerts, P. R. Pintrich & M. Zeidner (Eds.), Handbook of self-regulation: Theory, research and applications (pp. 343-368). San Diego, CA: Academic Press.), the Rubicon model of action phases (Heckhausen, 1991 xClose
Heckhausen, H. (1991). Motivation and action. New York: Springer-Verlag.), the perspectives on change model of smoking cessation (Borland, Balmford & Hunt, 2004 xClose
Borland, R., Balmford, J., & Hunt, D. (2004). The effectiveness of personally tailored computer-generated advice letters for smoking cessation. Addiction, 99, 369-377.), the AIDS risk reduction model (Catania, Kegeles & Coates, 1990 xClose
Catania, J. A., Kegeles, S. M., & Coates, T. J. (1990). Towards an understanding of risk behavior: An AIDS risk reduction model (ARRM). Health Education Quarterly, 17, 53-72.), and theories of delay in seeking health care (e.g., Andersen, Cacioppo & Roberts, 1995 xClose
Andersen, B. L., Cacioppo, J. T., & Roberts, D. C. (1995). Delay in seeking a cancer diagnosis: Delay stages and psychophysiological comparison processes. British Journal of Social Psychology, 34, 33-52.).

Different stage theories use different definitions and measures of stages. This article uses the TTM and the PAPM to illustrate the construct of stage and how it is measured. First, the two theories will be briefly described.

The Transtheoretical Model

The TTM is the dominant stage model in health psychology and health promotion. It was developed in the 1980s by James Prochaska and colleagues at the University of Rhode Island. The model includes several constructs, with the stages of change providing the basic organizing principle. The most widely used version of the model specifies five stages: precontemplation, contemplation, preparation, action and maintenance. People are assumed to move through the stages in order, but they may regress from action or maintenance to an earlier stage. People may cycle through the stages several times before achieving long-term behavior change. The model has been applied to a wide range of health behaviors, with smoking cessation still the most frequent application.

The TTM has been very influential and has popularized the idea that behavior change involves movement through a series of stages. It has also stimulated the development of innovative interventions. However, the TTM has attracted a large amount of criticism over the years, culminating in a recent call for the model to be abandoned (West, 2005 xClose
West, R. J. (2005). Time for a change: Putting the transtheoretical (stages of change) model to rest. Addiction, 100, 1036-1039.). The main problems with the model concern the definition and measurement of the stages (discussed below) and the lack of a clear specification of which variables influence which stage transitions. In addition, most supportive research has relied on cross-sectional designs rather than stronger research designs, in particular longitudinal studies of stage transitions and experimental studies of matched and mismatched interventions (Sutton, 2005 xClose
Sutton, S. (2005). Stage theories of health behaviour. In M. Conner & P. Norman (Eds.), Predicting health behaviour: Research and practice with social cognition models (2nd ed., pp. 223-275). Maidenhead, England: Open University Press.; Weinstein et al., 1998 xClose
Weinstein, N. D., Rothman, A. J., & Sutton, S. R. (1998). Stage theories of health behavior: Conceptual and methodological issues. Health Psychology, 17, 290-299.).

The Precaution Adoption Process Model

The PAPM was originally developed to describe and explain the process by which people adopt precautions against a new risk, i.e., one that they have recently learned about rather than one they have been aware of for some time. For example, the model was applied to understanding the adoption of precautionary behavior after warnings were released about the high levels of radon in homes in specific geographic areas. It is also applicable in the situation where a new precaution against an "old" risk becomes available (e.g., the introduction of the HPV vaccination to prevent cervical cancer).

The model specifies seven discrete stages. The model specifies seven discrete stages. In Stage 1, people are unaware of the health issue. People in Stage 2 are aware of the issue but they have never thought about adopting the precaution; they are not personally engaged by the issue. People who reach Stage 3 are personally engaged but they are undecided about whether to adopt the precaution. If they decide against adopting the precaution, they move into Stage 4, or out of the sequence of action adoption. If they decide in favor, but have not yet acted on this decision, they are in Stage 5. People who act on their decision move to Stage 6. Finally, for some behaviors, a seventh stage (maintenance) may be appropriate.

Although only a handful of studies using the PAPM have been conducted to date, it is a promising approach that avoids some of the problems with the TTM. For example, it defines the stages without reference to arbitrary time periods and, e.g., between having never thought about adopting a particular precaution and having thought about it and decided not to act. Key tasks for future research on the PAPM are to specify the variables that are important for each of the stage transitions and to test whether they predict and influence these transitions.