Yes, as a natural nervous laugher myself I had to course-correct later in life and learn to have gravitas. It is never beneficial to laugh, even if your counter

Yes, as a natural nervous laugher myself I had to course-correct later in life and learn to have gravitas. It is never beneficial to laugh, even if your counter-part is emotionally intelligent enough to know that it's nervous laughter because: 1) Your counter-part may not be emotionally intelligent enough 2) Deep-down, even if you know someone is showing you a nervous laugh it takes yet another level of emotional discipline to not be annoyed by it (like parents telling their kids "it's not funny".) I can't stress enough how much extra trouble I got myself into by being a nervous laugher and no one telling me any better. As a child when you nervous laugh, the typical response from an adult is typically ~ "Oh yeah, let me double down and show you how not funny this situation is" which implicitly is trying to be a punitive lesson in life to change your behavior. All this to say, this kind of police training/question is just cops making up pseudo-science and, as someone else pointed out, "heads I win, tails you lose" situation.