Social media not only make information more accessible, but also encourage the spread of conspiracy theories. To the areas in which conspiracy theories are attributed negative consequences count vaccination and climate change. Today, infection rates of diseases such as measles and mumps are on the rise again in many industrialized countries, which is associated with a decline in vaccinations. This is encouraged by increasing activism against vaccination, often based on conspiracy theories. In addition, conspiracy theories that doubt the existence of manmade climate change or downplay its consequences circulate. In this project we investigated the influence of the belief in conspiracy theories in the context of vaccination and climate change and how to counteract it.

Frequently mentioned reservations about vaccination consist of its possible negative health consequences and the presumption that these negative effects are concealed by the pharmaceutical industry due to economic interests. For the rejection of manmade climate change, for instance, the accusation of scientists being corrupt is of importance. Such and similar explanations reflect a so-called conspiracy mentality, which plays a decisive role in the rejection of vaccinations and scientific evidence (e.g., regarding climate change). However, little is known about the exact mechanisms that contribute to the concrete attitudes among conspiracy believers.

In this project, we therefore investigated under which conditions and through which mechanisms conspiracy beliefs affect behavioral intentions in the domains of vaccination and climate protection. A special focus was placed on factors that have already been associated with conspiracy theories (e.g. the rejection of societal norms, see project "Conspirational thinking and social influence"). Furthermore, we pursued the question why conspiracy believers are less receptive to positive communication about vaccination, e.g. through governmental information campaigns. In this context, trust in the source of communication as well as confirmatory processing were examined more closely.