The first possibility to check about others’ intentions is the most basic one -- their degree of openness (or its opposite). It's the most basic, because if people are open to each other, communication can begin. If they are not, nothing good can happen.
With a little practice, you
should be able to size people up very quickly along these lines on an almost
automatic basis. Don't look for an instant read, however -- what people call 'thin slicing' these days. In practice, it takes
some time to establish a baseline of behavior with each new person you meet.
The point is not to be able to perform this task instantly, but to be able to
size someone up within a few minutes, with high reliability, in terms of
whether this person is open to you.
Because people are so active with their eyes, you need to be careful to rule out environmental reasons. Is a bright light shining in the person’s face? That may account for narrowed eyes. It may not be because you’ve just offered the person a used car at an unbeatable price. If you can, look at the pupils. How open or shut are they? Openness indicates interest, attraction, and arousal; the opposite indicates the reverse. Of course, the general level of lighting in the environment also affects the pupils, so you need to establish a norm.
I'll continue with the rest of the face and body in the next blog. I go into much more detail about this in my book, Trust Me: Four Steps to Authenticity and Charisma.

