The technical term here is conspiracist ideation, which measures someone's confidence in explanations of events that rely on the power of groups to manipulate outcomes to an unlikely, if not near impossible degree. For the study's purpose, the researchers considered conspiracy theories to be beliefs that aren't supported by any evidence – and which are actually contradicted by the evidence that does exist.
These can be anything from believing the Moon landing was staged to thinking that legitimate elections are rigged.
In the case of COVID-19, conspiracy theories include the idea that the pandemic was largely exaggerated by the government or the media, and the belief that the virus was released on purpose by a particular agency for sinister means.
"It's speculative, but it appears that once people adopt one conspiracy belief, it promotes distrust in institutions more generally – it could be government, science, the media, whatever," says psychologist Russell Fazio, from The Ohio State University.
"Once you start viewing events through that distrustful lens, it's very easy to adopt additional conspiracy theories."