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).
Where did you see an option to choose your country?
After you finish the survey, it asks your age, gender, country and political position (from a drop-down that goes from “Extremely Liberal” to “Extremely Conservative”).
Oh, I thought they would asking for it before the survey begins and the questions are tweaked accordingly. It isn’t really fair to ask someone from the other side of the world questions solely based on US politics.