Chewing or sucking on the frames of the glasses signifies deep thought. Pens placed in the mouth have the same effect. The glasses can be shaken from side to side signaling a rejection of an idea. The finger wag or shake by itself is quite overt and powerful whereas the glasses shake is more tempered. Boredom can also be signaled with glasses, such as folding and unfolding them repeatedly. Bending glasses at the center can indicate agitation, and touching the tips signal tension or stress. Putting the glasses back on means the person wants to see more of the facts, setting them aside can mean that the meeting is over and throwing them aside altogether or dropping them abruptly means full rejection.
Moving the glasses up on the forehead can signal honesty but peering over the glasses is a classic evaluative gesture that signals scrutiny and judgment. Peering over glasses is the discerning librarian or catholic school teacher bearing down on naughty students. Studies show that we also rate wearers of glasses as being more studious, intelligent, sincere and conservative, although having particularly thick glasses negates those positive attributes. We think thick glasses are for those with low social skills who are overly-intelligent (geeks or nerds).