Health Education Research, Vol. 14, No. 5, 641-651,
October 1999
© 1999 Oxford University Press
A critical examination of the application of the Transtheoretical Model's stages of change to dietary behaviours
School of Psychology, University of Leeds, Leeds LS2 9JT and
1 Institute of Food Research, Reading Laboratory, Reading RG6 6BZ, UK
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Abstract |
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This paper proposes that the application of the Transtheoretical Model's stages of change to dietary behaviours may be fundamentally problematic due to the difference in nature between dietary behaviours and the addictive behaviours upon which the model was originally based. It was considered that specific problems associated with stage categorization for dietary change would include: problems due to the potential mismatch between a person's perceived and actual dietary behaviour; and problems due to the use of specific time periods to distinguish between different stages. A total of 541 volunteers completed questionnaires that measured their stage of change with respect to one of three dietary behaviours (healthy eating, eating a low-fat diet, and eating five portions of fruit and vegetables per day). Results indicate that people who were actively making a change (actors) or maintaining a change (maintainers) had done so for a range of different periods of time, with no specific cut-off point being evident. Also, more realistic stage categorizations were evident for the most specific dietary behaviours where there was least likelihood of a mismatch between perceived and actual dietary behaviour. Problems associated with issues of operationalization of the model and the application of the stage model to dietary change are discussed.
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Introduction |
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The Transtheoretical Model of behaviour change was originally developed by Prochaska and DiClemente (Prochaska and DiClemente, 1984
, 1986) within a clinical context to describe the process of behaviour change for addictive behaviours. In the latest formulation (Prochaska et al., 1992), they suggest that individuals pass through a series of five stages when attempting to change their behaviour, the first three of which are motivational and the remaining two actional stages. The first stage is referred to as the precontemplation stage, where the individual does not intend to change his or her behaviour in the foreseeable future. It is suggested that many people at this stage are unaware, or under-aware, of their problems. Next is the contemplation stage, where the individual is aware that a problem exists in relation to that behaviour and is seriously thinking of overcoming it, but has not yet taken action or made any preparations. The third stage is the preparation stage, where individuals have decided to take action in the next month and have been unsuccessful in taking action in the past year. Then comes the action stage, where the individual actually changes his/her behaviour. The final stage is the maintenance stage, where the individual is attempting to maintain the behaviour change by working to prevent relapse. In addition, the action and maintenance stages have strict time frames, in that people are described as being in the action stage if they have changed their behaviour for a period of 1 day to 6 months and as being in the maintenance stage if they have changed their behaviour for more than 6 months.
Although Prochaska et al. (Prochaska et al., 1992) described the direct application of their research to be in the clinical context where there is a need to `assess the stage of a client's readiness for change and to tailor interventions accordingly' [(Prochaska et al., 1992), p. 1110], the Transtheoretical Model has since been widely applied outside of its clinical context. One context where it has been frequently used is that of health promotion, where it is often employed to assist health-related behaviour change by classifying people into different stages and then providing them with the appropriate stage-based intervention. It has been applied to numerous different health-related behaviours other than those which are addictive, including exercise adoption (Lee, 1993), condom use (Bowen and Trotter, 1995), blood donation (Chandler and Ferguson, 1996) and HIV prevention (Prochaska et al., 1994). Among the studies which have examined health-related dietary change, it has been mainly used to examine fat reduction [e.g. (Curry et al., 1992; Bowen et al., 1994; Greene et al., 1994; Sporny and Contento, 1995; Steptoe et al., 1996; Brug et al., 1997b)], although it has also been applied to fibre intake (Glanz et al., 1994), fruit and vegetable intake (Campbell et al., 1994; Laforge et al., 1994; Brug et al., 1997a; Lechner et al., 1998), and the more general behaviour of healthy eating (Institute of European Food Studies, 1996). Each of these studies has tended to focus on the variation of different variables across the stages of change such as the advantages and disadvantages of the behaviour or `decisional balance' (Velicer et al., 1985), dietary intake, and various psychosocial variables. However, although substantial evidence is provided to show that different variables vary considerably across the stages, there is still some question as to the extent to which such variables are actually predictive of change. For example, although several studies have found self-efficacy to increase from the motivational to the actional stages (Glanz et al., 1994; De Vries and Backbier, 1994; Sporny and Contento, 1995; Brug et al., 1997a,b), there is no real evidence showing the extent to which self-efficacy influences people's movement across the different stages. Indeed, it could be argued that the cross-sectional designs predominantly used in this type of research are not entirely appropriate for testing such influences on the movement of people across stages, only providing a weak test of a stage theory (Weinstein et al., 1998). Only when a longitudinal design is employed, which would be more in line with the temporal nature of the model, would it be possible for such information to be obtained.
In addition to these problems associated with the application of stage theories to health behaviour change, several authors have noted that differences between dietary behaviours and the addictive behaviours upon which the model was originally based may cause problems for the model (Bowen et al., 1994; Sigman-Grant, 1996; Ni Mhurchu et al., 1997). One such difference concerns the goal or end-point of the behaviour change. With addictive behaviours such as smoking, the goal is to abstain from the addictive behaviour completely, whereas for dietary behaviours, the goal of `eating a healthy diet' could be described as a more general behaviour or behavioural `category' (Fishbein, 1997) which is open to greater individual interpretation (Povey et al., 1998). Problems may arise when such interpretations do not coincide with the current nutritional guidelines, perhaps leading some individuals to perceive incorrectly that they have made `healthy' modifications to their diets when they have not. Ni Mhurchu et al. [(Ni Mhurchu et al., 1997), p. 14] have suggested that the complex nature of diet may lead to people being categorized in more than one stage: `For example, someone may have already made dietary changes and sustained those changes for a year (maintenance) while recognizing that there are further dietary changes that are necessary or desirable and planning to make them in the future (contemplation)'. Indeed it seems to be agreed that `lack of a clear commonly known stable goal makes applying a model of behavior change less concrete and certainly more difficult' [(Bowen et al., 1994), p. 87].
The possibility that people may perceive themselves to have made `healthy' modifications to their diets when they have not, i.e. that they may be unaware of or have misunderstood the nature and extent of the actual dietary change carried out, could be said to have serious implications for the application of stages of change models to dietary behaviours. Previous studies which have examined the extent to which people are aware of their actual diet [e.g. (Brug et al., 1994; Lechner et al., 1997; Povey et al., 1998; Lechner et al., 1998)] report there to be a large discrepancy between the objective assessment of diet and self-rated, subjective intake. It could be suggested that the method of self-completion questionnaires which is frequently used to categorize people into different stages of change will be open to such misperceptions. This may result in an over-representation of people who perceive themselves to be currently engaging in the behaviour (i.e. in the action and maintenance stages of change) and fewer people perceiving themselves to be in the motivational phases. For example, a person who incorrectly perceives him/herself to have been eating a low-fat diet for 6 months or more may classify him/herself as being in the maintenance stage, when he/she may be more realistically classified in an earlier stage of change.
Finally, despite its popularity, no standardized procedure has been developed for the categorization of people into different stages of change and those methods of categorization which have been devised have tended to use time-related techniques to distinguish between the stages. These time-related techniques have been used particularly to distinguish between the action and maintenance stages, with the majority of studies specifying a time period of 6 months to distinguish between the two, the length of which some authors have referred to as `arbitrary' (Sutton, 1996, 1997; Bandura, 1997; Weinstein et al., 1998). Indeed the whole idea of categorizing people into a specific stage merely by the length of time they have spent engaging in the particular activity seems somehow to contradict one of the preliminary conditions for stage models, i.e. that people in one stage will have `qualitatively' different attributes from those in another (Bandura, 1997; Weinstein et al., 1998). Some authors have argued that when this time-dependent technique is used to distinguish between action and maintenance, `the latter [maintenance] is simply an extension of the former [action] rather than a qualitative transformation of it' [(Bandura, 1997), p. 8] and it has been noted that any alteration of the time frame may change the distribution of people across the stages (Weinstein et al., 1998). In addition to this argument, the use of fixed time-frames to distinguish between stages neglects to appreciate gradual change in behaviour which may have occurred over several years or the daily routinization of attempts to change and/or balance out unhealthy with healthy behaviours (e.g. eating chips followed by salad). However, as yet, the study by Bowen et al. (Bowen et al., 1994) appears to be the only published study which has used a technique based on `qualitative' distinctions in behaviour (e.g. people were classified as `actors' if they reported that they were trying to change their diet), rather than time limits to distinguish between the action and maintenance stages of change.
The study described in this paper developed a measure that focused on the `qualitative' differences between stages to classify individuals into different stages of dietary change for three dietary behaviours. These behaviours were: eating a healthy diet, eating a low-fat diet, and eating five portions of fruit and vegetables per day. The behaviours were chosen so that they varied in level of specificity: from eating a healthy diet, which was considered to be a very broad behaviour or behavioural `category' (Fishbein, 1997); to eating a low-fat diet which was considered slightly less broad although still problematic; and finally to eating five portions of fruit and vegetables per day, which was considered much easier to quantify if portion size could be established. It was considered that a behaviour which was more specific would represent a clearer goal, and therefore enable people to evaluate their behaviour more accurately and reduce the discrepancy between objectively assessed intake and self-reported intake. Such a reduction in the discrepancy between objectively and subjectively assessed dietary intake may cause a lower degree of misclassification in the action and maintenance stages, and possibly lead to more realistic stage classifications. It was hypothesized that the use of `qualitative', as opposed to traditional `time-dependent', techniques would result in a more realistic estimate of categories of stage of change. In an attempt to explore the relevance of time frames in greater depth, the study also examined the extent to which people used different time frames in their efforts to implement dietary change.
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Method |
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Sample
Volunteers were recruited on two separate occasions as part of a larger study (Povey, 1997
), using advertisements placed in regional newspapers. The first advertisement was placed in a newspaper during November 1995, recruiting 269 respondents, 242 (90%) of whom completed and returned a questionnaire concerning `eating a healthy diet'. The majority of this sample was female (71%). About half (51%) were either married or living as married; of the rest, 33% were single, 11% were divorced or separated and 5% were widows or widowers. Twenty-eight percent were highly educated with a degree or higher degree, 32% had `A' levels or HNC/HND qualifications and the remainder had qualifications up to `O' level or GCSE. Respondents' ages ranged between 13 and 90 years; the median age was 38 years old. The second advertisement was placed in a newspaper in March 1996 and recruited a total of 388 respondents, half of whom were sent a questionnaire concerning `eating a low-fat diet', the other half were sent a questionnaire concerning `eating five portions of fruit and vegetables per day'. One hundred and forty-eight out of 194 respondents (76%) completed and returned the low-fat questionnaire, and 151 out of 194 respondents (78%) returned the fruit and vegetable questionnaire (total N = 299). About two-thirds (68%) of the sample who responded to the low-fat questionnaire were female and just over half (55%) were married or living as married. Thirty percent were single, 12% were divorced or separated and 3% widowed. In this sample, 14% had a degree or higher degree, 29% had qualifications up to and including `A' levels or HNC/HNDs, and just over half the sample (57%) had educational qualifications up to `O' levels or GCSEs. Respondents' ages ranged from 16 to 81, with a median age of 41.
Finally, the majority of the sample who completed the fruit and vegetable questionnaire was once again female (72%). Just under half of the sample (47%) were married, or living as married, 39% were single, 7% were divorced or separated, and 6% were widowed (one person did not answer this question). Thirteen percent of the sample had a degree or higher degree; 32% had qualifications up to and including `A' levels or HNC/HNDs, and just over half the sample (54%) had educational qualifications up to `O' levels or GCSE standard.
The total sample size for the three dietary behaviours was 541, comprising 242 from the first advertisement and 299 from the second (71% female; 29% male).
Materials
Questionnaires were developed for each behaviour. Each questionnaire included some questions to assess the demographic characteristics of the sample together with a measure to categorize respondents into the different stages of change. For full details of materials, see Povey (Povey, 1997).
Measures
Respondents were initially asked whether they were `currently trying to eat a healthy diet' or `currently in the process of changing to a low-fat diet/changing to eat five portions of fruit and vegetables per day'. Responses were either `yes' or `no'. If they replied `yes' to this question they were then asked about the length of time they had been making this change with possible responses: `less than 1 month', `about 1–3 months', `about 4–6 months', `about 7–9 months' and `more than 10 months'. The next question asked whether they were currently eating a healthy diet/low-fat diet/five portions of fruit and vegetables per day (responses either `yes' or `no'). If they replied `yes' to this question, they were then asked whether they had changed their diet (`yes' or `no'). If they replied `yes', that they had changed their diet, they were then asked about when they had changed, once again with one of a possible five responses ranging from `less than 1 month ago' to `more than 10 months ago'. There were then two questions asking whether the respondent was `thinking about' or had `decided to' eat a healthy diet/low-fat diet/five portions of fruit and vegetables per day in the future. Possible responses were either `yes' or `no'. If they replied `yes' that they had decided to make this change, they were then asked about the most likely time that they would begin to eat this diet. There were six possible responses to this question, these were: `from now on', `beginning in the next few days', beginning in the next few weeks', beginning in about a month', beginning in the next few months' and `beginning in the distant future'.
If respondents indicated that they were not currently trying to eat a healthy diet nor in the process of changing to eat a low-fat diet/eat five portions of fruit and vegetables per day, they were categorized in one of the motivational stages (i.e. precontemplation, contemplation or preparation). They were categorized as precontemplators if they responded that they were not thinking about nor had decided to engage in the dietary behaviours in the future; as contemplators if they responded that they were thinking about, but had not decided to engage in the behaviours in the future; or as preparators if they responded that they were thinking about and they had decided to engage in the dietary behaviours. Respondents were classified as actors if they replied that they were currently trying to eat a healthy diet or in the process of changing to a low-fat diet/eat five portions of fruit and vegetables per day. Finally, they were classified as maintainers if they perceived themselves to be currently engaging in the dietary behaviour and had already changed their diet to do so.
Procedure
Each respondent was asked to complete two questionnaires, the second of which was sent to them upon the successful completion of the first (for the questionnaires concerning low-fat intake and eating five portions of fruit and vegetables per day, the second questionnaire was actually sent 1 month after the return of the first). On receipt of both completed questionnaires, the respondent was sent a cheque (£4 if they completed the healthy eating questionnaire; £5 if they completed the low-fat intake/five portions of fruit and vegetables questionnaires). The data obtained from the questionnaires were analysed using SPSS for Windows (Norusis, 1993).
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Results |
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First, the respondents were classified into one of the five different stages of change for each dietary behaviour using the categorization method described above. The percentage distribution of respondents across the different stages is displayed in Figure 1
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It can be seen from Figure 1
that for healthy eating there was a very highly skewed distribution of respondents across stages of change, with only a small minority of people classified in the motivational stages of precontemplation, contemplation or preparation (13.9% in total), and the vast majority (85.5%) being either in the action (32.2%) or maintenance (53.3%) stages of change. For people eating a low-fat diet, on the other hand, over a third (40.5%) of the sample were classified as being in one of the motivational stages, and just over half (52.0%) in the action and maintenance stages, with the majority of respondents (41.2%) being categorized in the maintenance stage. Finally, for the categorizations of eating five portions of fruit and vegetables per day, over half (54.3%) of the sample were in the motivational stages of change, and just over a third (39.7%) were in the action or maintenance stages. The categorizations for this behaviour appeared to be fairly evenly spread across the five stages, with a higher level of precontemplators (23.8%) and a lower level of maintainers (23.8%) than either of the other two behaviours. For each behaviour, a small number of respondents were categorized as `unclassifiable' if their responses did not fit clearly into any of the five stage categorizations (healthy eating, 0.4%; eating a low-fat diet, 7.4%; eating five portions of fruit and vegetables per day, 6.0%). It should be noted that although the method used to categorize individuals into different stages of dietary change produced different distributions across the three dietary behaviours, there also appear to be similarities between them. For example, for each behaviour, the least number of respondents was found to be categorized in the preparation stage and the majority of respondents was found to be categorized as maintainers (although the number of maintainers was actually equal to the number of precontemplators for the behaviour of eating five portions of fruit and vegetables per day).
Next, the different time frames existing for people classified as actors, maintainers and preparators were examined. It may be recalled that respondents who reported that they were preparing to change their diet (preparators), were actively changing their diet (actors) or had already changed their diet (maintainers) were asked to indicate when they were most likely to make the change (preparators), for how long they had been making the change (actors) or for how long they had changed their diet (maintainers), respectively. The questionnaire offered a number of possible time-scales which varied from `from now on' to `beginning in the distant future' (preparators) and from `less than a month' to `more than 10 months' (actors and maintainers). Table I shows a comparison of the different time frames indicated by people at different stages of change.
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Although the responses obtained from actors and maintainers varied from `less than a month ago' to `more than 10 months ago', it can be seen from the results displayed in Table I
that only 17.9% of actors from the healthy eating questionnaire said that they had been changing their diet for less than or equal to 6 months, with the vast majority (82.1%) saying that they had been making the change for more than 6 months (i.e. the majority would be categorized as `maintainers' using traditional time-dependent measures). In comparison, 68.8% of actors from the low-fat questionnaire, and 75.0% of actors from the fruit and vegetable questionnaire said that they had been changing their diet for less than or equal to 6 months. For maintainers, on the other hand, 83.6% of maintainers from the healthy eating questionnaire said that they had changed more than 6 months ago, compared with 73.7% of maintainers from the low-fat questionnaire, and 69.5% of maintainers from the fruit and vegetable questionnaire. Finally, for each behaviour, preparators were found to give a variety of responses (ranging from `from now on' to `in the distant future') concerning when they would be likely to begin eating a healthy diet/low-fat diet/five portions of fruit and vegetables per day; 62.5% of preparators from the healthy eating questionnaire, 83.3% of preparators from the low-fat questionnaire, and 76.5% of preparators from the fruit and vegetable questionnaire said that they would eat the respective diet in about 1 month or less.
In summary, from the results it can be seen that one of the main differences between the classifications of the three dietary behaviours is that the proportion of respondents classified in the action and maintenance stages is largest for `healthy eating', with gradually smaller proportions of people classified in these two stages as the behaviours become more specific. It could be suggested that such differences may be due to the fact that the more general behavioural category of healthy eating actually includes the separate behaviours of `eating a low-fat diet' and `eating five portions of fruit and vegetables per day'. Thus more people could be expected to be eating (or perceive themselves to be eating) a healthy diet in a general sense than eating, specifically, a low-fat diet or five portions of fruit and vegetables per day. Other possibilities could be that the differences may be due to the nature of the different samples or perhaps due to the different ways in which the general behaviour of `healthy eating' can be interpreted (Povey et al., 1998), leading some people to perceive themselves to be eating healthily when they are not (as judged by objective criteria). In addition, the results also seem to lend support to the view that the traditionally imposed time distinctions (i.e. 6 months to distinguish between action and maintenance) are arbitrary and do not necessarily fit in with the ways in which people appear to behave.
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Discussion |
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The `qualitative difference' method used in this study to categorize people into different stages of change provided stages which were comparable to those obtained in previous studies using time-dependent methods [e.g. (Curry et al., 1992
; Greene et al., 1994; Institute of European Food Studies, 1996; Steptoe et al., 1996)]. Similarities were found across the dietary behaviours in that for each behaviour it was found that the majority of people were classified as maintainers and the minority as preparators. It could be argued that this gives some validity to the measure, since people would be more likely to be situated at the longer lasting steady states of precontemplation or maintenance, rather than the short-lived, more transient stages of change (such as preparation or action). Results also showed that people who were actively making the change (actors) and people who were attempting to maintain the change (maintainers) had done so for a range of different periods of time, and no 6 month cut-off point was evident to distinguish between the two. In addition, although the majority of actors for low-fat and fruit and vegetable intake reported that they had changed less than 6 months ago, most actors for healthy eating reported that they had been making the change for 6 months or longer (82.1%). The time-dependent method of categorization would classify such individuals as being in the maintenance rather than the action stage, resulting in an over-representation of people in the maintenance stage or `pseudomaintainers' (Steptoe et al., 1996). These results therefore appear to provide support for the argument that time-dependent methods of stage categorization are less appropriate for use with complex and varied health behaviours such as dietary change, than for use with the addictive behaviours upon which they were originally based. In addition, these results do appear to provide some empirical evidence in support of the theoretical argument that the period of 6 months is merely an `arbitrary' cut-off point (Sutton, 1996, 1997; Bandura, 1997; Weinstein et al., 1998) between the action and maintenance stages. These results would therefore provide support for the view that it may be more appropriate to use methods which categorize people into stages of dietary change by distinguishing between the `qualitative' attributes between them (Bandura, 1997; Weinstein et al., 1998) and suggest that such methods appear to produce a more realistic estimate of stage categorizations. It may be useful for further research to examine the use of such methods with different health behaviours and to investigate which variables, in addition to the classification criteria, predict membership at each stage.
In addition, the results appeared to suggest that as the behaviours became more specific (i.e. from `eating a healthy diet' to `eating five portions of fruit and vegetables per day'), the proportion of people in the motivational stages increased, and the proportion of people in the action and maintenance stages decreased. It is possible that these differences in distributions may be explained by a higher proportion of people trying to eat a generally healthy diet (which may incorporate specific behaviours such as `eating a low-fat diet'), than trying to eat a specifically low-fat diet or five portions of fruit and vegetables per day. However, it could also be suggested that such a trend may merely reflect the extent to which people tend to misperceive their diet. That is, it seems reasonable to suggest that people are less likely to perceive accurately whether they are actively engaging in general, widely interpretable behaviours [or behavioural `categories' (Fishbein, 1997)] such as `healthy eating', than would be the case with more specific behaviours such as `eating five portions of fruit and vegetables per day'. It is therefore possible that people may incorrectly perceive themselves to have made `healthy' modifications to their diets when they have not, creating a `mismatch' between their perceived and actual diet (Sparks et al., 1996), and therefore leading to an over-representation of people in the action and maintenance stages. It could be argued that such `mismatches' which appear to be present between actual and perceived dietary behaviour would be unlikely to occur among the addictive behaviours upon which the model was originally based, once again leading us to question the extent to which the model, in its current form, is applicable to dietary behaviours.
Some stage researchers have attempted to overcome such problems by re-classifying people at different stages of change according to their actual behaviour [e.g. (Greene et al., 1994; Brug, 1997)]. Greene et al. (Greene et al., 1994) proposed a model in which people in the action or maintenance stages who did not eat less than 30% fat would be re-classified into the preparation stage; Brug (Brug, 1997), on the other hand, proposed a model in which self-reported maintainers who eat high-fat diets would be re-classified as precontemplators who are unaware of their `risk' behaviour. However, re-classification of people into different stages does not appear to resolve the problem completely. Indeed it poses a separate problem, i.e. is it plausible to combine people who believe that they are eating healthily with those who do not into a single psychologically meaningful stage? From a health promotion point of view, it may be a better alternative to treat maintainers who are not actually eating `healthily' as a separate group and design interventions accordingly. In any case, it would be interesting to carry out further research on people who believe they are eating healthily and find out the `qualitative' differences between those who are actually eating a healthy diet and those who are not. Also, it may be useful for methods to be employed which help increase the accuracy with which people are able to assess their diet. One such method which has been employed is individualized dietary feedback (Sparks et al., 1996; Brug, 1997), where the person is provided with information concerning his/her own current dietary intake. Such techniques are likely to be useful not only for the classification of people at appropriate stages, but also on a larger scale as health promotion techniques for the promotion of healthy eating amongst the general population.
Before concluding, it is important to draw attention to some of the limitations of the study. Firstly, the sample was a convenience sample (i.e. recruited through a newspaper advertisement) which was predominantly (71%) female. It is possible that people recruited in this manner may be more highly motivated to change their behaviour and that the disproportionate number of women compared to men may have produced some influence on the results. In future studies it would be interesting to compare alternative methods of recruitment and also to examine in detail whether the distribution of stages may be explained by characteristics of the sample. In addition to these limitations, it could be argued that the use of self-completion questionnaires to categorize people into stages of change will always be prone to some form of bias. These include problems in the way in which questions are phrased or misconceptions of the questions by the respondent (Glanz, 1995) and social desirability bias (Crowne and Marlowe, 1960; Kristiansen and Harding, 1984; Herbert et al., 1995). Although attempts have been made to overcome such problems in designing the questionnaires in the present study (Povey, 1997), it is almost impossible to eradicate them entirely and it is necessary to be aware of such possible limitations when interpreting the results.
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Conclusions |
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In conclusion, the results from this study add to the growing `thicket of problems' [(Bandura, 1997
), p. 8] associated with application of stage theories to health-related behaviour change. The results suggest that not only are there fundamental problems with the traditional time-dependent methods used to classify people at different stages, but also specific problems associated with the application of the model to diet. It could be suggested that such findings give weight to the argument that `human functioning is simply too multifaceted and multidetermined to be categorized into a few discrete stages' [(Bandura, 1997), p. 8], thus casting doubt over the validity of stage models as a whole. They also lend support to the argument that behaviour change might be more appropriately described in terms of a `continuum' (Sutton, 1996, 1997), possibly divided into `pseudo-stages' (Weinstein et al., 1998) as opposed to five discrete stages. However, it could also be argued that the main criticisms stem from psychologists failing to recognize the limitations of such models, by taking them out of the clinical context for which they were originally intended and employing them as tools to help understand and predict health behaviour change. Indeed, it should be noted that the original stage models were only designed as descriptive devices to enable clinicians to create appropriate interventions for people with addictive behaviours, rather than predictive techniques to explain influences across the process of change. In conclusion, the results from this study would suggest that further research examining the application of the Transtheoretical Model's stages of change to dietary and other health behaviours would benefit from the development of a tool which categorizes people into different stages by focusing on the `qualitative' distinctions between them, rather than the length of time spent making the change. In addition it is important for researchers and health professionals who are employing the model within different health contexts to be fully aware of the limitations to the model and its application outside of the clinical environment.
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Acknowledgments |
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This study was carried out as part of a UK Economic and Social Research Council funded project entitled `Ambivalence About Health-Related Dietary Change' as part of `The Nation's Diet' Research Programme (reference no. L209252040).
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References |
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Received on January 14, 1998; accepted on September 17, 1998
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