Sorry, I have to disagree. Pulling the hand away and yelping strengthens the dogs bite inhibitions. Most pups learn it in the nest from their litter mates and dam. I have never seen a dog that reacted any differently than mouthing more gently and finally giving it up as a bad idea. Our pups at Guide Dogs were homed at six weeks to enable socialisation to have the maximum benefit and this was the method used by puppy walkers. Those adolescents that came to kennels for training that were mouthy from not been taught otherwise were succesfully re-educated with this method. I have used it since with all breeds and ages. I have never seen a prey drive response to it.