"The more I think about it, the less I like it": Effects of elaboration, narrative transportation, and freedom threat on the effectiveness of HPV vaccination advocacy messages.

Approximately 80 million US adults-one in four-are infected with the human papillomavirus (HPV), which causes cancers of the cervix in women, cancers of the anus, penis, and throat in men, and genital warts in both sexes. Although HPV vaccinations are safe, effective, easily affordable, and readily available, a substantial percentage of parents resist recommendations to vaccinate their children against HPV. The current study tests the effects of different vaccination advocacy message strategies on attitudes toward HPV vaccination. Study participants (N = 963) were randomly assigned to one of four message conditions (a narrative story, an informational fact sheet, an appeal from an expert spokesperson, or an identical appeal from a nonexpert spokesperson) and assessed for change in attitude toward HPV vaccination along with levels of elaboration, narrative transportation, and freedom threat caused by the messages. Analyses showed that the messages' effects on attitude change were mediated by transportation and moderated by freedom threat. With the informative, expert, and nonexpert messages, increased message engagement produced increased freedom threat. With the narrative message, increased message engagement produced reduced levels of freedom threat. For risk communicators and planners of health interventions, the results suggest benefits for using a nonexpert advocacy message when levels of message engagement are expected to be low and using a story-based narrative advocacy message when levels of message engagement are expected to be high.