That is true, but then they should have made a control test where they give complicated but true sentences to the same people, checking if they obey to the auth

That is true, but then they should have made a control test where they give complicated but true sentences to the same people, checking if they obey to the authority of the language as well. In that case they are not susceptible to bullshit, but merely have given up on 'elite' discussions. Which might both explain voting for Trump and working in Mechanical Turk.