In this brilliant video by Vania Heymann, he address the anxiety felt by strangers when walking beside each other - when in synchrony. This is an example of what in body language terminology is known as "mirroring". Whenever people who know each other mirror each other too exactly in time or configuration - it creates anxiety - and destroys rapport. In contrast, somewhat less exact mirroring can build rapport and is also a natural phenomenon and expression of intimacy between people who are in love, good friends, strongly bonded, etc.
Mirroring with strangers immediately creates a false intimacy and, as the narrator in Heymann's piece points out - a distancing in space (or uncoupling in synchrony) then occurs. A lack of mirroring in effect, insulates us by increasing the psychological distance between us and others - while mirroring closes our interpersonal space and makes us feel vulnerable and metaphorically naked.
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