Effects of Prior Exposure to Conflicting Health Information on Responses to Subsequent Unrelated Health Messages: Results from a Population-Based Longitudinal Experiment.

BACKGROUND Accumulating evidence suggests that exposure to conflicting health information can adversely affect public understanding of and trust in health recommendations. What is not known is whether prior exposure to such information renders people less receptive to subsequent unrelated health messages about behaviors for which the evidence is clear and consistent. PURPOSE This study tests this "carryover" effects hypothesis, positing that prior exposure to conflict will reduce receptivity to subsequent unrelated health messages, and examines potential affective and cognitive pathways through which such effects might occur. METHODS A three-wave, online, population-based survey experiment (N = 2,716) assessed whether participants who were randomly assigned to view a series of health news stories and social media posts featuring conflict at Times 1 and 2 were ultimately less receptive at Time 3 to ads from existing health campaigns about behaviors for which there is scientific consensus, compared to those who saw the same series of stories and posts that did not feature conflict. RESULTS Structural equation modeling revealed evidence of carryover effects of exposure to conflict on two dimensions of message receptivity: greater resistance to the unrelated ads and lower perceptions of the health behaviors featured in the ads. Modeling indicated that carryover effects were a function of generalized backlash toward health recommendations and research elicited by prior exposure to conflicting information. CONCLUSIONS Findings suggest that the broader public information environment, which is increasingly characterized by messages of conflict and controversy, could undermine the success of large-scale public health messaging strategies.