Words vs. body language
"I told her no" he said walking away with his dog continually jumping on him. "But, that is not what you said with your face or body," I told him. "She only sees action right now, she is not listening to your words," I explained as I have done so many times before. Our dogs watch us far more than they listen to us. Just the other day I was outside with Luke and Elsa when Miss Elsa lifted her leg and almost peed on Luke. Yep, she is a marker and on this day she could not wait for him to finish before marking over his pee. I yelled as she lifted her leg which stopped her short of hitting him on the leg. I was postured adding to the disapproval in my voice which had great effect. She very quickly ran over and sat in front of me with just the very tip of her tail wagging from under her rear end. She understood very clearly that it is not okay to pee on Luke. Honestly.
What you say and what you do are two completely separate things. You can say one thing but if you do not follow up with actions your words may be lost. Of course, this is with regards to feedback and not well trained verbal cues. It also depends on the individual dog, your relationship and training. If you want to be very clear you will make good use of your body as well as your voice when trying to get a message across to your dogs. You might say "stop, stop, stop, STOP," but it is not until you get up or stand tall that they listen. Young dogs are often the culprit of this "I can't hear you," scenario. They may be at the push stage and giving things a try. But add some body language in with your vocal feedback and you will then be speaking dog.
Using your body, facial expression and vocal or verbal are all options. You can use only body language on all it's own to deliver a message. Eye contact works well on it's own with a dog who is use to looking for it. But vocal or verbal does not always work on it's own. If you have a well trained dog who knows when you speak that you mean business then yes it will work wonderfully. But if you have a young dog or a dog who is never given feedback or expected to follow orders at all then you may have a difficult time.
Elsa is a body language dog, she is constantly watching and perfecting it. If she is mooching at the table for scraps, I simply have to freeze and look at her to send her flying away from the table. If I stare at her she gets very uncomfortable as she tries to figure out what she is doing wrong. For these type of dogs it does not take a lot to get a message across. Others may need more practice for their reading skills and some need new lessons altogether. Most dogs come to us with a clear understanding of body language; it is important to keep it up so that they don't lose it. It is also the easiest way to communicate with them.
Watching a fine tuned canine/human team work together is amazing. That doesn't mean that they have to be doing agility, flyball or other sport. It can be simply how they interact on a day to day basis. Anyone can have it, with just a bit of work. But that work will pay off tenfold.