Researchers want the public to test themselves: https://yourmist.streamlit.app/. Selecting true or false against 20 headlines gives the user a set of scores and a “resilience” ranking that compares them to the wider U.S. population. It takes less than two minutes to complete.
The paper
Edit: the article might be misrepresenting the study and its findings, so it’s worth checking the paper itself. (See @realChem 's comment in the thread).
It’s exactly those “reasonable” sounding headlines (and in some cases the ideas and opinions that back them up in the body of the article, but that has to be provided for it to relevant, which as you point out isn’t, which is a big problem) that serve as misinformation and/or dog whistles, so “vaccines contain harmful chemicals” could be aimed at antivaxxers (and those susceptible to being pushed there), but it’s also technically correct, for example apples and bananas contain “harmful chemicals” too.
The article could be either fear mongering and disinformation - false, or science based and educational - true, but we can’t know which just from the headline.
A headline like “small group of people control the global media and economy” could be a dog whistle for antisemitism - false, or be an observation of life on earth right now - truth.
My point is there are headlines that would seem like conspiracy theory to some, but irrefutable fact to others, and probably the opposite of each to each respective group, and without more than a headline (and often even with, of course), it’s entirely down to the readers’ existing opinions and biases.
Not a great way to test this.