Understanding The Role Of Different Types Of Affect In Health Behaviours

The past two decades have witnessed a growing shift in the application of health behaviour science towards the exploration of affect as a determinant of health behaviour. Affect-related constructs are potentially important because they influence behaviour through intention, and they can influence behaviour directly. However, in social health science, different types of affect are seldom considered simultaneously. Therefore, the main aim of this thesis was to investigate, via correlational and experimental studies, the extent to which different types of affect (affective attitude, anticipated affective reactions and intrinsic motivation) are important in predicting and changing intentions and health behaviours.
The findings related to the correlational evidence are presented in Chapters 3, 4, 5 and 6 (Studies 2, 3, 4 and 5) and show that three affective variables showed a significant interrelationship, and they all had significant correlations with both intentions and behaviour. The results of all the studies show that all three affective variables significantly predict intention. Interestingly, the three variables predicted behaviours differently depending on the behaviour type. Chapter 3 (Study 2) shows that affective attitude and anticipated affective reactions significantly predicted behaviours to protect against COVID-19. Meanwhile, Chapter 4 (Study 3) shows that intrinsic motivation significantly predicted behaviour, while affective attitude and anticipated affective reactions did not. The experimental evidence (Chapter 2; Study 1) shows that a meta-analysis of 39 studies that tested the effects of interventions to change affect reported small-to-medium-sized changes in overall affect-type variables and similar-sized changes in health behaviour. Furthermore, effect sizes reflecting changes in affect predicted effect sizes reflecting changes in health behaviour. The results for specific types of affect (intrinsic motivation, affective attitude and anticipated affective reactions) also showed small-to-medium effect sizes for all three affect variables, whereas the effect for another affect variable, introjected regulation, exhibited a small effect size. Furthermore, the interventions did not significantly influence positive or negative affect. Only effect sizes reflecting changes in intrinsic motivation predicted effect sizes reflecting health behaviour changes. The findings in Chapter 5 (Study 4) show that intervention messages targeting affective attitude significantly changed it. Conversely, intervention messages targeting intrinsic motivation and anticipated affective reactions did not significantly change them. Chapter 6 (Study 5) shows that, even after the re-development of this manipulation, interventions aimed to predict changes in intention, physical activity behaviour and these three affect variables did not statistically significantly change any factor.
The findings of this thesis underscore the pivotal role of affect in health behaviour. Affective attitude and anticipated affective reactions emerge as distinct factors, while the dominance of intrinsic motivation over affective attitude remains unclear, with correlational and experimental findings presenting contrasting results. This underscores the challenge of manipulating these two affect variables, particularly when attempting to manipulate each one independently. Further research is warranted to determine the most effective approach to manipulating these three affect factors, with the aim of predicting changes in intention, health behaviour and affect variables themselves.