The role of usability, usefulness and frame in persuasive health communication

Background: A large proportion of ill-health is preventable (Signorelli 1993). A goal for health promoters is to provide information about health risks with the aim of persuading individuals to modify their behaviour. Previous research suggests that the readability of many health promotion materials is too low for effective comprehension. Evidence suggests that much of the health information available is written at a level that is too difficult for the target populations (e.g. Dollahite et al. 1996, Meade & Byrd 1989, Greenfield et al. 2005). Whilst this work is useful in identifying barriers to accessibility to health information, there has been little research that systematically explores the concept of usability within the context of health information. Objectives: The first objective of the thesis was to examine whether the concepts of usability and usefulness as outlined in the Technology Acceptance Model (Davis 1993) can be applied to the domain of health promotion and used to predict intentions to follow the advice given in health promotion leaflets. Second, the studies sought to make distinctions between subjective and objective usability and to explore the factors underlying subjective ratings of the usability of health information. Further, the thesis sought to demonstrate that both objective and subjective usability would influence the persuasive effect of health promotion materials. Finally, using theory from dual-processing models of persuasion (e.g. Elaboration Likelihood Model. Petty and Cacioppo 1986) it was predicted that when usability of leaflets was high, participants would be more likely to make judgements about their intentions to follow the advice given in the leaflets based on peripheral clues such as frame (Tversky and Kahneman 1981, Rothman and Salovey 1997, Levin et al. 1998). Methodology: 5 empirical studies examined the research questions. The first study consisted of two samples from working populations (n=441), and explored manual handling and use of hearing protection. Participants evaluated existing health and safety leaflets in relations to their usability and usefulness, and rated their intentions to follow the advice in the leaflets. The second study, also conducted on a working population (n=97), used experimentally manipulated leaflets on safe manual handling to test the hypothesis that framing effects would be found when usability of leaflets was high. The third study used a student sample (n=127) to explore factors that influence subjective usability. The study used experimentally manipulated leaflets about safe alcohol consumption to examine whether the concept of subjective usability is a function of reader characteristics (psychological constructs, mood, past exposure to the health problem) and leaflet characteristics (frame, objective reading ease). The fourth study used a student sample (n=238) to test the effect of objective reading ease on recall, in order to test for differences in processing of two experimentally manipulated leaflets about safe alcohol consumption. It was predicted that easy leaflets would be processed at a more shallow level than difficult leaflets. The fifth study, also conducted on a student sample using experimentally manipulated safe alcohol leaflets (n= 135), used pre and post testing to further explore the effects of usability on framing effects, and to test for a moderating role of prior knowledge on the effect of usability on intentions. Results: The studies showed that readers distinguish two separate components to health information leaflets: usability and usefulness. Subjective perceptions of usability and perceived usefulness predicted intentions to follow the advice given in the leaflets. Objective usability (reading ease) influenced the persuasive effect of the leaflets, with easy leaflets being more persuasive than difficult leaflets. Perceived usefulness partially mediated the relationship between subjective usability and intentions. Objective reading ease affected recall, with easy leaflets resulting in higher levels of both accurate and false recall of the information in the leaflets. Prior knowledge moderated the relationship between usability and intentions. Those with low prior knowledge were more persuaded when usability was high. Usability influenced the effect of frame on intentions. Framing effects were only found where usability was high. Where framing effects were found, negative frame was more persuasive than positive frame, offering support for Levin et al.'s (1998) typology of framing effects. Conclusions: Results from the studies show that the concepts of usability and usefulness, formalised in models of technology acceptance (TAM), can be applied to health information and used to predict intentions to follow health promotion recommendations. A distinction can be made between subjective and objective usability, and both of these can influence persuasion. Using theory from dual-processing models of persuasion, usability of health information leaflets can influence the effect of frame on intentions to follow the health promotion advice.