LAUSR

The influence of presumed influence hypothesis (IPI hypothesis) explains that people have biased perceptions of media influence and they change their behavior based on such perceptions. This study explicated the mechanisms of influence of presumed influence in health communication by integrating the theoretical explanations of the IPI hypothesis with theories of normative influence. The causal chains of the IPI hypothesis were examined using an experimental methodology with a HIV prevention, PrEP (pre-exposure prophylaxis). The results supported the expectations. Presumed exposure to health messages about PrEP shaped presumed influence of the messages on others, which in turn affected one's own intentions for information seeking and prosocial behaviors about PrEP. The findings also show that descriptive norms and injunctive norms interact with presumed influence differently. This study discusses the potential benefits of the IPI hypothesis in health communication.