BEHAVIORAL INOCULATION An effective communication strategy to induce resistance towardsAn effective negative communicat internet messagesion strategy about to the induce HPV resistance-vaccination? towards negative internet messages about the HPV-vaccination? Written by: Marloes Beerling (890725-044-040) Supervisors: Dr. L. Mollema Dr. E.W.M.L. de Vet MSc programme: Applied Communication Science Specialization: Strategic Communication in Innovation Wageningen University Department of Social Sciences MSc Thesis Chair Group: Knowledge, Information and Technology 0 Abstract Background In 2009, the vaccination against the Human Papillomavirus (HPV), the virus that can cause cervical cancer, was included in the National Immunization Programme for 12 and 13 year old girls. The uptake of the HPV- vaccination was lower than expected (50%). It is believed that one of the main reasons for the low vaccination rate was the negative and incorrect media coverage about the vaccination, specifically on the internet. Therefore, communication tools are needed to make parents of 12 and 13 year old girls more resilient towards these media messages. The inoculation strategy (McGuire, 1961) is such a communication tool and posits that individuals can be made resistant to persuasive attacks by exposing them to weak arguments against their current attitude, including a refutation of these arguments (McGuire, 1961). The purpose of this study is to assess whether McGuire’s inoculation theory is an effective strategy to strengthen the attitudes of parents towards the HPV-vaccination. Methods An online two-phase experiment with three conditions was carried out among 390 parents and guardians of 12 and 13 year old girls. Phase 1 consisted of a baseline measurement. In addition, during phase 1 participants in condition 1 were asked to read a message written according to the principles of behavioral inoculation and participants in condition 2 were asked to read the mini-magazine that is currently used by the RIVM to inform parents about the HPV-vaccination. Condition 3 was the control condition. Seven days after the participants completed phase 1, participants were invited to take part in phase 2 of the experiment. The participants read a persuasive attack in the form of a vaccine-critical internet message and filled out the follow-up measurement. Resilience towards persuasive messages was assessed by the outcome variables attitude extremity (how positive or negative parents are towards HPV-vaccination) and attitude certainty (how certain parents are about their attitude towards HPV-vaccination). Results Participants in the inoculation condition (condition 1) did not have a greater feeling of threat than participants in the mini-magazine and the control condition, indicating that the experimental inoculation manipulation was not successful. Overall, the participants who received the mini-magazine scored higher at follow-up on attitude extremity and attitude certainty scores than the participants in the inoculation and control condition. All participants got more negative at follow-up measurement on attitude extremity scores, especially the prior positive and high involved participants; this negative change was significant for the inoculation and control condition. Conclusions Behavioural inoculation is not an effective strategy to induce resistance to persuasion on the topic of HPV- vaccination. The behavioural inoculation treatment was less effective than the currently used HPV mini- magazine and only slightly more effective than not giving any additional information to the parents. Therefore, implementation of texts written according to the principles of behavioral inoculation is not recommended. In addition, the results suggest that the persuasive attack was responsible for the negative attitude change among parents. This finding indicates that more attention needs to be paid to strategic communication interventions that induce resistance towards negative media messages on the topic of HPV-vaccination. Keywords Inoculation theory, behavioral inoculation, HPV-vaccination, public communication 1 Table of Contents 1. General Background _____________________________________________________________________ 4 1.1 Introduction _______________________________________________________________________ 4 1.2 Problem Statement _________________________________________________________________ 5 1.3 Research Objective _________________________________________________________________ 5 1.4 Overview of this report ______________________________________________________________ 6 2. Theoretical Framework __________________________________________________________________ 7 2.1 Inoculation Theory __________________________________________________________________ 7 2.1.1 The inoculation mechanism __________________________________________________________ 7 2.1.1.1 Threat _______________________________________________________________________ 7 2.1.1.2 Refutational preemption ________________________________________________________ 8 2.1.2 Additional factors that influence behavioral inoculation ____________________________________ 8 2.1.2.1 Inoculation time _______________________________________________________________ 8 2.1.2.2 Issue involvement ______________________________________________________________ 9 2.1.2.3 Valence of prior attitude ________________________________________________________ 9 2.2 Operationalizing resistance to persuasion _______________________________________________ 9 2.3 Empirical review___________________________________________________________________ 10 2.3.1 Empirical support for behavioral inoculation ____________________________________________ 10 2.3.2 Empirical review of behavioural inoculation in health promotion ___________________________ 10 3. Sub questions & hypotheses _____________________________________________________________ 12 4. Research Method ______________________________________________________________________ 14 4.1 Target population _________________________________________________________________ 14 4.1.1 Characteristics of dropouts __________________________________________________________ 14 4.1.2 Deletions ________________________________________________________________________ 15 4.2 Research design and procedure ______________________________________________________ 15 4.2.1 Procedure ________________________________________________________________________ 15 4.3 Information interventions ___________________________________________________________ 16 4.3.1 Inoculation message (condition 1) ____________________________________________________ 16 4.3.2 Information brochure HPV-vaccination {condition 2) _____________________________________ 17 4.4 Variables _________________________________________________________________________ 17 4.4.1 Background variables _______________________________________________________________ 17 4.4.2 Main variables __________________________________________________________________ 18 4.4.3 Manipulation check ________________________________________________________________ 19 4.4.3 Covariates _______________________________________________________________________ 20 4.4.4 Evaluation measures _______________________________________________________________ 21 4.5 Statistical analysis _________________________________________________________________ 21 5. Results _______________________________________________________________________________ 22 2 5.1 Description of participants __________________________________________________________ 22 5.1.2 Comparison study population with Dutch population _____________________________________ 22 5.2 Distribution of variables ____________________________________________________________ 23 5.3 Randomization check _______________________________________________________________ 24 5.4 Manipulation check ________________________________________________________________ 24 5.5 Correlations between covariates and outcome variables __________________________________ 26 5.6 Hypothesis testing _________________________________________________________________ 26 6. Discussion and Conclusion _______________________________________________________________ 32 6.1 Main results ______________________________________________________________________ 32 6.1.1 Finding 1 _________________________________________________________________________ 32 6.1.2 Finding 2 _________________________________________________________________________ 33 6.2 Limitations _______________________________________________________________________ 33 6.3 Practical implications _______________________________________________________________ 34 6.4 Recommendations for future research _________________________________________________ 34 6.5 Final conclusions __________________________________________________________________ 35 Acknowledgements _______________________________________________________________________ 35 References ________________________________________________________________________________ 36 Appendices_______________________________________________________________________________ 40 3 1. General Background 1.1 Introduction Cervical cancer is the second most prevalent type of cancer among women in the Netherlands (RIVM, 2013). Every year 600 women are diagnosed with cervical cancer and on a yearly basis 200 - 250 women die because of this disease in the Netherlands. Cervical cancer is caused by the Human Papillomavirus (HPV), a virus transmitted through sexual intercourse.