The chameleon effect is fun as you watch a gesture or posture wave pass through a group. I for some reason felt that I saw more of it on Japanese film crews, but I have no way to verify this. Also, I wonder what the current state of study is for those who are imitated the most often. The obvious answer would be those that are respected and have what would be considered higher status, but maybe there are some not so obvious reasons affecting how likely you are to be copied. Are certain gestures far more fluid (yawning) and socially mobile? And our these imitations a set that are basically hardwired across the board or are they culturally malleable so that you can mirror far more complex or particular actions from cultures you are familiar with, but perhaps would be lost elsewhere?
Also, a lot of this sounds incredibly optics based–what do the blind do?