I find this somewhat questionable. I would self report as a believer in conspiracy theories like:

* CIA using mind control studies on unwitting participants (https://en.wikipedia.org/wiki/MKUltra)

* A former US President conspired to try a putsch on the US Government on Jan 6th

* Russia is using Social Media farms to influence large scale of people (and that a lot of the degenerated political discourse in my home of Germany is fueled by it

* The German Secret Service (Verfassungsschutz) is deeply involved in the Murders of the NSU Terrorist Cell and itself infiltrated by right wing groups its supposed to protect us from

* The United States has Significant Data on UFOs that they are keeping from the people in Special Access Programs.

And so on. All of those were or are conspiracy Theories but they are either outright proven to have happened (first 3) or have significant evidence to back them up.

I am kinda doubtful those are the ones this study is concerned with though.