This seems completely unrelated to the comment you're responding to. They were asking how the study figured out what the private opinions were, not about what sort of opinions they were hiding.
I disagree. The question by parent was how it is determined. I merely provided several ways to determine the out-group as determined by the in-group. It is very relevant and, frankly, apt.
No, it's not. I think the thing they were asking could be rephrased as "How did the researchers figure out what private beliefs people held if those beliefs were private?"
How does "Wrong hat. Wrong phrasing. Wrongthink." remotely answer that? Those are labels of particular types of actions/beliefs. They are not explanations of how researchers would find out something that people usually keep secret.
The method is always the same. It is mildly depressing, but not surprising.
Amusingly, or sadly - I did not decide yet - just the other day, I openly declined to discuss Tate for that very reason in public.