I once read teaching dogs and children things were very similar.
I use hand signals as well as verbal for Kass and Erns and they get just as confused if my hand isn't the same each time as if a word sounds similar to something they know.
On a more serious note, when training at home in general obedience I had used hand signals along with voice even at a distance; and this made the last year of Auggie's life, when she was totally deaf, a bit easier on both her and us.
At distance on free walks she would look to us and we would/could signal "right", "left", "wait", or "come". And in the house all it took was a hand gesture rather that using one's whole arm. I highly recommend training to gestures, not only for the possibility of deafness but also having more control/communication under circumstances of high wind and/or noisy conditions.
Rush understands pointing. Point to something on the floor and she has to see what you're pointing at (usually a crumb) Point to a toy and she will go over to it and either pick it up or mouth it a little. Point out the window and she goes to see what she should be looking at. It doesn't work every single time but I'd have to say probably 90%. Boo, no clue as to what you are pointing at or what it means.
I also use a distinct hand/arm signal for all Puff's verbal commands, e.g., ours are: "sit" = bang fist once on imaginary table, "come" = slap my chest with the palm of my hand, "down" = point finger at the ground, "speak" = imitate an opening duck bill with thumb & palm, etc.
I think it was last year, someone published an experiment on a remarkable dog in Europe that knew the names of over 400 objects. When told to go to another room and bring back the __Q__ , the dog would always bring back the correct object.
IIRC, they then placed a new object that the dog had never been trained on among the other familiar ones and asked it to fetch a ==X== and the dog brought it back apparently because since it wasn't familiar with the name of that object this new object must be the right one.
I think that may be quite a bit smarter than the average 2 year old -- certainly smarter than Puff.
zoe started in the hand signals class and her MOM = me got bored and quit.
Interesting though...I was taking a pic of the other two and said to zoe motioning with my hand; "get over there with them some i can get your pic". freaky thing is that she did it!!!!!!
Interesting article, I have to say that Sammi understands my hand signals as well, if not better then any verbal commands I give her. However I do use hand signals far more then verbal with her! I have no idea why, since I have no trouble talking, just ask DH