Lordy, how many times have I heard newbie pet owners say to me that
their dogs are soooo smart because they know hand signals???? 
I've been reviewing the Ian Dunbar books and tapes that I have, as I'm going to his three day seminar soon (Science Based Training with Feeling). On the "Training Dogs With Dunbar" video, there's a wonderful demo of a lady with a Bearded Collie that I wish every new dog owner would watch. It's just a classic on how dogs learn our body language first, and our verbal cues later. It completely and quickly dispels the notion that dogs are being stubborn when we tell them to do something, versus simply being unable to understand the cue as we've given it. Now I know where my mentor got this simple demo that many of us have been using for a long time in our classes with great success (I use it when I'm teaching the transfer of the "down" hand signal to the verbal "down" cue). Lol, Dr. Dunbar is a whole lot more gray now than he was in the clip I just watched!