But even then, how would you know what normal hand movement is for the particular person in front of you? Some people gesture a lot, some don't. Does that mean people who dramatically gesture are lying all the time? Of course not.
Lucky for me, when I'm searching my brain for a fact or figure while I'm talking, for some reason I glance up to the left. It just feels like there's more there than on the other side (or I like to kid myself, anyway) And I'm right-handed. Since all of this is public knowledge, then anyone intent on getting away with lying could just change the cues they give you. Even lie detector tests can be defeated. The only reliable test is to verify, verify, verify.
Your Constructive Comments are Welcome!