Investigating the short-term familiarity backfire effect in the context of vaccination ------------------------------------------------------------------------ Emily Kothe, Mathew Ling *Misinformation Lab, School of Psychology, Deakin University* Attempts to counteract misinformation have had mixed effects, occasionally resulting in "backfire effects", where pre-existing beliefs are entrenched rather than refuted. This study tested for short-term familiarity backfire effects (where repetition of a myth before correction results in increased belief in the myth) in the context of vaccination. Participants (n=234) were recruited through ProlificAcademic and were randomised to one of two variants of a pro-vaccination message (one with myth repetition and one without) or a control message about bird feeding. There were no differences in willingness to vaccinate or vaccine related beliefs between individuals who received a pro-vaccination message and those that did not (p's>.05). Short-term familiarity backfire effects were not observed in this study. However, the messages were also not effective in influencing individuals' beliefs about vaccination. Understanding the factors that underlie intention to vaccinate is required in order to aid in the development of more effective persuasive messages.