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,
Rothman & Sutton, 1998).
Stage is the central construct in the transtheoretical model
& Velicer, 1997), the precaution adoption
process model (PAPM; Weinstein,
& Sandman, 1992),
the stage version of the health action process approach (HAPA;
the health behavior goal model (Maes
& Gebhardt, 2000), the Rubicon model of action
1991), the perspectives on change
model of smoking cessation (Borland,
Balmford & Hunt, 2004),
the AIDS risk reduction model (Catania,
Kegeles & Coates, 1990),
and theories of delay in seeking health care (e.g., Andersen,
Cacioppo & Roberts, 1995).
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). 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,
et al., 1998).
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.