Communicating about xenotransplantation: models and scenarios.

Xenotransplantation entails using organs from genetically modified animals as a way to solve the shortage of human organs for transplantation. As with other novel technologies, if xenotransplantation is to be judged fairly, proponents must explain its complex, uncertain, and unfamiliar risks and benefits. Xenotransplantation's risks include the possibility of a recombinant virus infecting human transplant recipients, potentially causing an epidemic of an unfamiliar disease. Using materials vetted by scientific experts, we communicated the variables and relationships determining this risk in three formally equivalent formats: (a) a graphic model, (b) scenarios structured by the graphic model, and (c) both the model and the scenarios. Participants were randomly assigned to receiving one set of materials. They rated them as equally clear and studied them equally long, suggesting similar ease of cognitive processing. Compared to participants receiving the scenarios, those who received the graphic model better identified causes and effects of the risk, and saw less risk of xenotransplantation. Participants who received both the model and the scenarios generally showed intermediate responses. The study demonstrates a general procedure for developing and evaluating formally equivalent graphic and scenario communications regarding highly uncertain risks. In this application to xenotransplantation, presenting a graphic representation improved people's understanding of the risk.