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Category: Project

Description: Efficiently communicating information on vaccination is crucial to maintaining a high level of immunization coverage, but it implies finding the right content for the right audience. Most studies have tested the direct effects of messages on either anti-vaccine or vaccine-hesitant individuals. Pro-vaccination individuals, who represent the majority of the population and have been neglected in the literature, could play an important role relaying pro-vaccination messages through informal discussions. A pro-vaccination message is useful if pro-vaccination individuals (i) find it plausible, (ii) remember it, and (iii) are willing to transmit it. Studies in cognitive psychology and cultural evolution have found that the framing of messages can affect these different steps. We conducted a series of experiments on 2337 pro-vaccination online participants in the U.S. and U.K., testing whether the valence of a statement (positive or negative) and its rhetorical orientation (pro- or anti-vaccine) affected these three steps. Contrary to the advantage of negatively framed statements observed in the literature, in our experiments participants deemed more plausible and were more willing to transmit (but did not remember better) positively framed statements. Pro-vaccination rhetorical orientation had similar, but smaller, effects to those of positive framing. While the effects of valence were observed in both the U.S. and U.K. sample, the effects of rhetorical orientation were absent in U.K. participants. Overall, framing effects were dramatic: for instance, one framing made participants very eager to transmit a statement, while another made them reluctant to transmit it at all. Since messages have to be framed one way or the other, the framing effects demonstrated here should be taken into account when designing messages aimed at pro-vaccination individuals.