Stan Wawrinka beat Novak Djokovic to win his first US Open on Sunday. As he recounts, Wawrinka began using the gesture shown below a few years ago when he also beat Djokovic - but in the quarterfinals of the Australian Open.
From a body language perspective (depending on the other nonverbal signs with which it is clustered) this is a variety of an "Emblem" - although in some scenarios it may be an "Illustrator" or a "MAP" (Manipulator, Adaptor, Pacifier).
When pointing at one's temple simultaneously while looking at another person after a particularly good play, point, performance, etc., (usually for somewhat of a prolonged duration in a stare or modified stare), this nonverbal cluster functions as form of a "game face" for intimidation. Somewhat overlapping with this, it can also mean, "I've got you figured out" or "I'm smarter than you".
Yet when the same nonverbal sign is used while looking instead at the audience, this same emblem then primarily indicates a strong mental focus or mental strength.
In either scenario it also acts as positive feedback loop serving to amplify the positive feelings and reinforce the memory, thus making it more likely for its user to emotionally, mentally and physically re-create the experience in the future.
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