During COVID-19, conspiracy theories were intensely discussed in the media. Generally, both believing in conspiracy theories (i.e., explanations for events based on powerholders’ secret arrangements) and being confronted with a conspiracy theory have been found to predict cognition and behavior with negative societal effects, such as low institutional trust. Accordingly, believing in conspiracy theories around COVID-19 should reduce institutional trust, support of governmental regulations and their adoption, and social engagement (e.g., helping members of risk groups). We tested these predictions in a national random sample survey, an experiment, and a longitudinal study (N _total = 1,213; all studies were preregistered). Indeed, believing in and being confronted with a COVID-19 conspiracy theory decreased institutional trust, support of governmental regulations, adoption of physical distancing, and—to some extent—social engagement. Findings underscore the severe societal effects of conspiracy theories in the context of COVID-19.

在COVID-19期间，媒体上对阴谋论进行了激烈讨论。通常，既发现相信阴谋理论（即基于掌权人的秘密安排对事件进行解释）又遇到阴谋理论都可以预测具有负面社会影响的认知和行为，例如低机构信任度。因此，相信围绕COVID-19的阴谋理论应减少机构信任，减少对政府法规的采纳和支持，以及社会参与（例如，帮助风险群体成员）。我们在全国随机抽样调查，实验和纵向研究中测试了这些预测（_共N _个= 1,213; 所有研究均已预先注册）。确实，相信并面对COVID-19阴谋论会降低机构信任度，减少对政府法规的支持，采取疏远措施，并在一定程度上降低了社会参与度。这些发现强调了在COVID-19的背景下阴谋理论对社会的严重影响。