People say they don't like their dog begging, but they have only themselves to blame for the problem.

When we like the dog's behavior, we say we're "sharing" our food. When we don't like the behavior, we call it "begging." And we foolishly expect our dogs to see the difference.

If you never want your dog to stick her nose in your plate, put her head on your knee or paw at your arm, then don't ever reward her with food when she does.

What if it's too late for that? With patience and consistency, you can change your dog's behavior by never rewarding the begging again. When your dog finally becomes convinced that she will never again see another piece of food delivered from your plate, she'll stop asking. You can also have her practice a behavior that's incompatible with having her nose on your knee Ñ a down-stay on the other side of the room while you're eating.

But be warned: If you're inconsistent, you'll actually make the problem worse.

Rewarding a behavior occasionally is called random reinforcement, and it's a powerful motivator. In fact, it's what keeps the gambling industry afloat. Even though gamblers know the house always wins, they keep pulling the handle on those slot machines because they get a little back now and then, and because sometimes they hit the jackpot.

Dog trainers use these principles to instill good behaviors in dogs, but many pet lovers inadvertently use them to teach a dog bad habits -- like begging.