Two main implications of the findings are discussed: the importance of planning in implementation intentions interventions and the validity of the theoretical distinction between motivation and volition.

The implementation intentions intervention procedure, which encourages the use of environmental and contextual 'cues' to prompt a desired behaviour, appears to offer a promising strategy for encouraging the performance of TSE.

Measuring belief importance can help more fully identify the structures underlying attitude, subjective norm and perceived behavioural control, and can provide useful information when the TPB is used as the basis for intervention to help change behaviour.

OBJECTIVE: To examine the influence of an individually derived versus modal subjective norm component of the Theory of Planned Behaviour (TPB) in predicting attendance at breast screening. DESIGN: A prospective, longitudinal design was employed using a postal questionnaire at Time 1 and objective attendance data from screening records at Time 2. METHOD: Questionnaires were sent to 1000 women from East Kent due to be invited for X-ray mammography under the UK's National Health Service Breast Screening Programme. The TPB constructs were used to predict attendance, with a focus on subjective norm. Two versions of the questionnaire were distributed: one assessed subjective norm using individually generated normative beliefs (individual condition) and the other provided a list of modal referents (modal condition). RESULTS: The mean number of normative referents in the individual condition was just two, almost all of whom were family members, in contrast to the modal condition where 'GP' led the rank table. The results suggest that a more senstive measure of subjective norm is attained using individually derived beliefs. Structural equation modelling revealed that, contrary to theoretical prediction, the effect on attendance of the individually derived subjective norm was not entirely mediated by intention: an independent contribution to attendance was shown. In the modal condition the construct was entirely mediated by intention. CONCLUSIONS: For health behaviours that have implications for others as well as self, measuring individually salient normative beliefs may both improve theoretical prediction and yield information of potential value for designing intervention programmes.

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link:http://openaccess.city.ac.uk/5529/ Link to published version: http://dx.doi.org/10.1111/j. 2044-8287.2011.02034.x Copyright and reuse: City Research Online aims to make research outputs of City, University of London available to a wider audience. Copyright and Moral Rights remain with the author(s) and/or copyright holders. URLs from City Research Online may be freely distributed and linked to. hypertensive medication is proposed and tested. The model suggests that adherence is influenced by three sets of variables: demography, health status and perceived effects of medication; cognitions and motivation; and intention to adhere. Methods and DesignPatients with known hypertension were recruited from three primary care practices in South-East England and were asked to complete a postal questionnaire. A total of 1070 responses were received. The questionnaire asked about the three sets of predictor variables, and adherence. Eight weeks after the first questionnaire, a second was posted to all respondents, this time asking about adherence over the intervening period. ResultsThe three sets of predictor variables were treated as blocks in a hierarchical model, so that each successive block added to the variance in adherence explained by the previous blocks. The data were analysed by hierarchical multiple regression. The predictors accounted for 19% of the variance in adherence at Time 1, and 34% at Time 2. The leading individual predictors at Time 1 were age, gender, conscientiousness, hypertensive identity, perceived behavioural control, and intention. At Time 2, they were the same, except that gender made way for adherence at Time 1. ConclusionsThe model offers a parsimonious account, and the findings suggest a number of approaches to designing interventions to modify behaviour. , 1997Horne & Weinman, 1999, 2002Legare, Godin, Dodin, Turcot, & Lapierre, 2003;Lynch et al., 2000;Schmier & Leidy, 1998;Trachtenberg, Dugan, & Hall, 2005). Despite these explanations, the social-psychological mechanisms involved in medication adherence are poorly understood and no single conceptual framework has been developed in which to study it (Morrell, Park, Kidder, & Martin, 1997).The aim of the present study was to investigate the predictors of medication adherence by developing a conceptual model, using a prospective longitudinal design to investigate possible causal pathways. This was pursued in the context of adherence to antihypertensive medication. We chose to study hypertension because it is a common conditionAdherence to anti-hypertensive medication 4 of 32 that is a risk factor for other potentially fatal conditions, such as myocardial infarction and stroke, and because blood pressure control in the UK is known to be sub-optimal --even among those treated for hypertension, of whom only half to two-thirds are thought to be adherent (Ebrahim, 1998;Primatesta, Brookes, & Poulter, 20...