"He wants to go out."
"He wants you to play with him."
"He wants you to pet him."
"He doesn't like you doing that."
Dog owners spend a lot of time interpreting and acting on their dog's vocal and body language signals. It is an ongoing and interactive non-verbal discourse between members of two completely different species. Let's look into how this happens a little more closely. Vocal Communication
Dogs are not big on vocal communication, but they do produce various types and intensities of sounds, ranging from whimpering and muttering to growling and barking, and, through this means, achieve some crude communication with other dogs and humans. Dogs may be better at communicating with humans in this way than with other dogs.
For example: Dog barks furiously (high energy bark – excitement over seeing a squirrel on TV)
We try opening the door (maybe he wants to go out?)
Dog thinks we're strange – but registers what has transpired
Dog wants to go out – tries a few things that don't work and then remembers the effect of barking. Tries it out and it works
Stimulus-response association is strengthened and high energy barking becomes the signal for going out
The corollary to this communication struggle is human/dog vocal communication. Dogs are by no means linguists: For them, English is a second language. But they do recognize a number of human sounds and are particularly attuned to hard consonants; sounds like "cuh" and "teh" (the word CAT is particularly easy for a dog to appreciate). The late, great Barbara Woodhouse knew this all too well and she favored (and popularized) one-word commands like siT, ouT, waiT, and stoppiT. Dogs can learn literally hundreds of human sounds, but they are no good at stringing them together. You can teach a dog to sit when you say SIT and you can teach him the word DINNER, but when you tell him "SIT IN YOUR DINNER" he will be at a loss as to what to do. That's where body language comes in to fill the communication gap.
Body Language Communication
Here the talents are reversed. Dogs are experts at sending and receiving body language signals and, in contrast, we are dumb clucks. The signs dogs use to communicate with each other are fairly well known and include certain facial expressions, body postures and movements (see Dog to Dog Communication.)
Of course, dogs try using these expressions to communicate with humans, assuming that we speak the same language. Some people understand what they see - and some don't. Although most humans understand extremes, such as the threatening expressions and postures of attack, the subtleties of canine "signing" are often overlooked or misconstrued.
Some people, rightly or wrongly, apply their own interpretation of dogs' body language. For example, the submissive grin of a self-effacing terrier may be interpreted by owners as a smile. The owners laugh and reward the behavior, which is thus conditioned and will later occur on cue; "Have you seen Bonzo smile?" an owner might ask her friend. On hearing the word SMILE, Bonzo then approaches, head and neck bowed and body wiggling, as he displays a super-reinforced submissive grin that looks for all the world like a human smile. Because everyone is happy about this novel event, the smile even appears to occur in context.
We humans aren't well versed in body language but we do have a little of our own. We stare in indignation and defiance. We crane our necks forward and jut out our chins by way of threat and lower our heads in submission and shame. We don't do much wiggling of our ears, and we don't have a tail to wag, but we do have hands that point or threaten. Even though dogs may not initially cotton on to the full significance of human hand jive, they do eventually get the message. Skillful trainers learn the importance of conveying a mix of signs, ranging from direct eye contact and forward body movement to hand signals, when giving a command. One deaf Dalmation, Hogan, knows 45 words of American Sign Language so the potential for learning in the signing department is large. Also, it has been recently shown that dogs can follow our gestures to find hidden objects. The fact that dogs display this talent means that dogs have evolved to understand us, their human caregivers, more than was previously believed possible.