To the skeptics: You don’t own a dog, do you? I think this debate will fairly well line up between those who have had dogs, and those who haven’t.
There are quite a few researchers who disagree with Chomsky’s notion about language being hardwired in humans.
It seems that you think research stopped with Pavlov and Skinner. It didn’t.
It’s obviously tone of voice. They wouldn’t react if I said “four score and seven kitty years ago, our kitty forefathers brought forth on this kitty . . .” That being said, it is not just tone of voice; if I say “Hatbox!” in the same excited voice, they may look at me (“She’s excited about something; better pay attention and look for more clues”) but they’re not running to the window to look around, all hyped up. I’m not really sure what you mean by body language in this context, but it’s not location either, as they’ll do in anywhere (car, my house, your house, the park) so long as you use the same “ooh, look!” tone of voice AND the same word. Another word doesn’t get the same reaction, which is why at our house “kitty” means any animal you want to bring to their attention, including horses and cows on the side of the highway.
And I don’t see the choice as either they’re flatworms or they can comprehend the complete works of Joyce. The OP asked for evidence the dogs can understand some words as standing for specific things or concepts, as opposed to commands. IME experience, they can. Off the top of my head, and in addition to commands, mMy dogs understand “bath,” “ball,” “cookie,” “wanna go for a ride?,” “kitty,” and “leash.” This doesn’t mean when I say “where’s your leash?” the dogs thinks “it’s in the kitchen.” But the dogs do know that “where’s your leash?” means we’re going for a walk now. And they know it beyond “she’s using a generalized exicited tone of voice; we’d better get excited too!” How do I know that? Because where you say “where’s your leash?” they get wound up and run back and forth from the front door (the exit used for walks) and when you say “wanna go for a ride?” they run back and forth from the garage door (the exit used for the car). I don’t think I’m using body language or tone to convey those differences; I think, in a limited way, they know what those few phrases mean.
Those two statements have to be examined separately. There are lots of people who disagree with Chomsky’s account of linguistic nativism - in fact, I don’t agree with it myself. But the belief that no language ability is built in is much less common; I’m aware that a few linguists still believe that (I read Geoffrey Sampson’s The Language Instinct Debate, in which he makes a case for exactly that) but it’s far from a common belief as far as I’ve seen.
The 200-word lexicon comes from this paper (requires subscription). Basically, they showed that a specific dog, “Rico” (a Border Collie, should you care) could learn and remember the names of about 200 specific objects (mostly toys), in some cases after a single exposure to the object and its name four weeks previously. Rico was considered to “know” a name if he could retrieve the named object on command; the experiments were pretty well controlled (although the total number of trials was low), with the named object mixed with several others (both new and familiar) and placed out of sight of the humans.
There is some slight evidence for grammar in that the owners said that Rico could be asked to fetch an item to a person other than the requester (i.e., he understood that “bring me the sock” was different than “bring John the sock”). This wasn’t formally tested and must be considered anecdotal.
The most interesting aspect of all this is that if Rico was asked to retrieve an item (out of a set of several familiar objects and one new one), using a name he had never heard before, he invariably retrieved the new item, suggesting that he was able to figure out that a unfamiliar name must refer to an unfamiliar object.
You can watch a movie of Rico fetching things here (free). There’s also a summary of methods and results (as a PDF file).
This doesn’t show that dogs have particularily good language skills overall. But it does indicate that at least one dog has a very good grip on the idea that a specific word refers to a specific object.
JRB
We’ve had dogs in front of whom we’ve had to avoid certain words in any tone of voice at all. “I’m going out to the store to get some milk,” within hearing of said canine would result in great excitement, as would, “I had to walk about a mile in the mall today.” The operative words being “out” and “walk.” We had to use long synonyms. “I’m going to go to, um, the exterior,” or “Let’s, uh, perambulate over to your mother’s house.”
OTOH, it is absolutely true that they respond to tone of voice. Anything said in an excited tone or loving tone elicits the expected response. I used to say, in that very affectionate tone one uses for animals, “Oooh, Neptune, are you an idiot? You ARE? Oh, what a stupid dog you are. You’re a complete moron!” And Neptune would pant and wag his tail in joyful agreement.
We also used to have a cat that, I swear recognized the phrase, “tuna fish sandwich.” “Hey, Hon,” my husband would ask, “Would you mind making me a tuna fish sandwich?” and Rocky would be in the kitchen prancing in anticipation before I got there. “…ham sandwich” said in the exact same tone got no response.
Perhaps we should say “You’ve never owned a bright dog, have you?” I’ve known a few dogs with questionable language acquisition skills. 
I love how when you get a new dog, (we got one from the pound recently) after a while they just seem to understand you. When you first get them and you talk to them, little things you say they don’t seem to really comprehend. (Some of this depends on their background, too.) After maybe 2 weeks, it seems like they understand most of what you say, if not in a complex way. Life gets easier with them. I’m not really talking about commands; more like the things mentioned above relating to food and activities and bedtimes and whatnot. If you have ever lived with a smart dog, it can be pretty amazing the way they can seem to understand you and make themselves understood, considering the inherent limitations of cross species communication. If they are responding mostly to tone, which some people seem to think, they must be pretty amazing at picking up subtleties in tone, because most people talk to their dogs in a sort of excited, higher-pitched tone a good deal of the time. I know if they were speaking in a different language, I wouldn’t be able to tell what they were talking about.
Well, when mothers shout at their little kids who have the same name as me, I always turn around and look, too. I can’t help it, something deep in my brain is sure they’re yelling at me.
The mention of different languages reminds me of the German Shepherd my husband had before we were married. His family speaks Ukrainian. The dog ONLY understood words in that language and would not respond to English at all or, at best, with a look of bewilderment, as if he knew I was trying to tell him something but he had no idea what it was. I used to say he was an East German Shepherd since he only took commands in Russian (the two languages are very similar).
I think the responses are based on this understanding of the OP: can dogs respond to words that are not commands? I would have responded that way as well: dogs can familiarize themselves with words that don’t involve an imperative.
At one point we had a very submissive dog and two very dominant cats. If we scolded the dog for any reason, the most dominant cat would come over an add her 2 cents’ worth, and a smack for good measure if permitted. One day I had to scold one of the children. Uh, oh, thought Dog. There’s yelling. I’m gonna get it. He went and hid under the table, only to be attacked by Cat. Poor puppy.
What if you said “go for a slide in the bar?”
I, personally, would consider millions of dog owners’ anecdotes to be evidence because they’re all pointing to the same conclusion: dogs are capable of understanding human speech in a limited way.
Dogs have been living with humans for thousands of years, easily long enough for humans to selectively breed such an ability. Humans and dogs can communicate with each other, and words are part of that communication.
It is clear that dogs can understand a word to mean a particular object, or a class of objects, like “ball.” Words can also mean a desired action, a command. “Walk” means an action that isn’t quite the same as a command. “Dog park” is a place, as is “mom’s house.”
My dogs know the names of all the other dogs they see on a regular basis, six in all, in addition to each other. My parent’s Golden knows each family member by name, but understands “ball” to mean any small, round object. It goes the other way, too: I know the difference between a bark that means “I need to go out” one that means “Yes, I really want to go to the dog park” and one that means “Something just made a noise outside, did you hear it?”
We used to have a dog that seemed to understand the concept of time, or at least the concept of “tomorrow.”
For whatever reason, “go bye-bye” came to mean “we’re going to get into the car and drive somewhere that you can run around and have fun at.” On a Saturday morning, if we’d say “want to go bye-bye?” we’d have the expected result of a hyperactive dog all but grabbing the car keys.
But - if we said “want to go bye-bye tomorrow?” she wouldn’t go nuts until the next day.
The trick, I suppose, would be in determining if that dog truly understood what “tomorrow” meant, or if the chunk of sound “want to go bye-bye” meant get in the car and go now, vs “want to go bye-bye tomorrow” was an entirely separate chunk of sound that meant “go somewhere in the car after sleeping.”
Our current dog will happily head for the door if you say “do you need to go out?” or “eat a bowl of sauerkraut” or “find a Boy Scout”
OTOH, she’s one of the denser dogs I’ve lived with and I’m not 100% sure her hearing is normal, although the vet’s not found any evidence of hearing impairment.
I have anywhere from 2-5 dogs depending on various dog-sitting parameters. The ones who spend the most time with me are extremely attuned to my body language and emotional state, as well as responsive to several verbal commands. I would be extraordinarily surprised to discover that they understand words as abtract symbols.
The question on the table is whether they understand words as anything other than commands. A good test would be to make a list of the words that you believe they understand, and put them together in such a way as to introduce an entirely new concept.
To use examples from this thread, if a dog understands “get,” “outside,” “ball,” and “tomorrow,” tell him to get the outside ball tomorrow and see if he does it.
Dogs are known to understand object permanence which has been demonstrated to show a basic concept of counting. If I put five red balls on a table, lower a screen and remove one ball and then raise the screen, most dogs will act surprised that one ball is missing, including searching for it. If they leave an object in a place, they expect to find it there when they get back.
Yes, a dog is an animal, but it’s a pretty smart animal. I keep hearing claims about dogs that are patently false: “They don’t understand words, just the tone of voice” - which is important, but not the whole answer. “They don’t mind eating the same food every day, they have no taste buds” - welcome to my kitchen, I will show you that they have indeed. Also, knowing how important smell is to us, when tasting food, what about dogs who have a sense of smell about 40 times more sensitive than ours*. “Dogs see in black and white, they are totally color blind” - No, they are not. Evolution has sacrificed some color vision in favor of improved night vision. Dogs tend to have an emphasis on blue/green, whereas red/yellow is less pronounced. But they see in color.
Why do people insist on downgrading dogs?
*Why then, is it, that with this fantastic sense of smell, dogs will stand still, with the snout half an inch from a steaming fresh dog turd, and deeply inhale the aroma for a very long time?
I used to impress people with my “multi-lingual dog.” I looked up the words for the commands that she knows in other languages and she would obey them the same as if I had spoken in English. I would eventually explain that it wasn’t a trick. I’ve tried the same thing on my other dogs and they respond the same way.
I believe that body language and tone of voice matter more to the dog than the word itself. Listen to yourself when you give the commands. When I say, “Sit”, I always drag the word out, “Siiiiiiit” with a small upward inflection at the end. When I say “Down” is said in more stern of a tone with the word itself short and clipped, and “come” is said in a high-pitched sort of breathless voice.
The way I do it may not be the way you do it, but I bet if you listen to yourself, you’ll discern a pattern in your voice and posture when you give commands. Often, our body language reveals more than we even realize. I noticed, for example, that when I was talking about bathing the dogs, I said “bath” in sort of a hestitant, secretive tone.
In other words, when I *expect *they’ll react to a word, the dog picks up on my slight tension in posture or inflection in tone of my voice, and that’s what they’re reacting to more than the word itself.
Our dog as a puppy hated the car. This was quite inconvenient for us, but we thought maybe it was because previously she’d only ever been taken to teh vet or the kennel. So we took her on a few trips to teh Burger King drive thru. And after about three trips she no longer hated the car.
Unfortunately, she’d learned the words Burger King and got excited any time our son asked to go. So we started referring to it as B K, until she caught on to that as well. We then switched to “beta kappa”. She was quite a bit older then and never cuaght on as far as we could tell in the last few years of her life.