In this Batman v Superman: Dawn of Justice promotional video, Henry Cavill interviews several children. He asks them (4-6 years old) which of the two superheros they favor, while discussing their various qualities and powers. Throughout the vast majority of these interactions, Cavill's forehead is contracted. This includes variations of the entire width of the forehead, isolated to the central forehead (CFC) as well as asymmetrical contractions (each of which have different sub-meanings).
Human adults have a strong tendency to over-use their forehead muscles when speaking to human children - and indeed we do so even to young animals. More specifically, we behave like this more often when they're not our own biological children. This behavior is a form of acting - and thus insincerity. We should NOT do this. Children can sense this melodrama at a much higher level of sensitivity than most adults ever realize.
Note that none of the children ever remotely contracted their foreheads as Cavill did many times - yet in this video, they're being touted as "brutally honest". Honesty is of course, sincerity as it is reflected in a single act or statement. The children (not actors) are thus being sincere with no use of their forehead muscles - while Cavill (a professional actor) is using his far too much in both frequency and amplitude.
This same behavior carries over when interacting with other adults. Moreover, if you had to say what is the most common nonverbal signal of insincerity? - It's over use of the forehead. Besides those who act this way around children, where else do we commonly see this nonverbal display?
1. Unskilled Actors (Those who are poor at the Stanislavsky method as well as Method Acting - unless perhaps they are playing one of the characters below)
2. News Anchors (Numbed to bad news)
3. Politicians (Very frequently insincere)
4. Sales Professionals (Those who don't believe in their product/service or are trying too hard)
5. Isolated Insincerity (Every person on occasion)
6. Chronic Insincerity (Antisocial Personality Disorder or colloquially known as Sociopaths)
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