Preventive and curative health decisions are often conceptualized as individual cost-benefit considerations. Some health decisions, however, also have consequences for other people. Nevertheless, these positive or negative effects on third parties (externalities) are neglected in the classical view as mechanisms and potential incentives in health decisions. Vaccinations, for example, often have positive externalities because they help to protect unvaccinated people by reducing the transmission of diseases. Antibiotic use, on the other hand, is an example of negative externalities, because excessive and improper use leads to resistance and uninvolved third parties can be harmed when antibiotics are no longer effective. Health decisions thus become social interactions when the decisions of several individuals and their health consequences influence each other and individual interests have to be weighed against collective interests.
In the preceding project "An interdisciplinary approach to explain and overcome vaccine fatigue", the vaccination decision was systematically analysed for the first time as a social interaction on the behavioural level. In three work packages of this follow-up project, we are now building directly on the proven research approach of analyzing social-interactive health decisions through interactive decision tasks (Health Games). It was repeatedly shown that prosocially oriented vaccination education is helpful to increase the willingness to vaccinate. In the first work package this will be critically examined with regard to facilitating and hindering moderators and mediators. Furthermore, studies from the previous project show that individuals are less willing to vaccinate if they perceive a lower effectiveness of the vaccination. Theoretical models, on the other hand, clearly show that this is normatively wrong, since with decreasing effectiveness indirect protection also decreases. Therefore, the follow-up project in the second work package is comprehensively devoted to the identification and evaluation of different debiasing strategies. The third work package transfers the research approach to antibiotic consumption and examines determinants of the intake decision in order to be able to develop strategies for reducing excessive antibiotic consumption in the future. For this purpose, a new interactive decision task has been developed, which models the social-interactive dynamics in the development of antibiotic resistance.
The work in this project extends theoretical models, since in the dilemmas described above, behavioral predictions change depending on whether the externalities of the individual decision are taken into account or not. The findings from this project contribute to the development of evidence-based interventions to reduce vaccine fatigue and excessive antibiotic use.