In my house, dogs are family. They get their own birthday celebrations and, despite my efforts to train them otherwise, they even get to sleep in the bed. I also talk to them, sometimes in praise, other times in a desperate attempt to convince them that it is not, in fact, in their best interest to eat crayons ... again. But how much of what I say to them do they actually understand? Do they remember the things I’ve told them? I know that I love my dog, but does my dog love me or just the food that I provide?
How many words can a dog know?
Most dog knows what you mean when you say “sit” or “stay,” and mine certainly knows the word “no,” but how much more can they understand? I know an English bulldog whose owners had to stop using the word “dinner” when doing their meal planning because their pup would think it was time to eat. For a while they switched to “supper” but he eventually learned that too.
Experts suggest that dogs on average understand somewhere between 100 and 200 words, a level of vocabulary typical of human 2-3 year olds. Some dogs, like those who live with deaf people, are also known to respond to hand signals even without verbal communication.
How dogs understand different words, however, is not well understood. For example, does your dog know that “shoe” is a thing you wear to protect your feet while walking outside? Or does your dog think the word “shoe” means “bring me that object I keep by the door”?
Common lore among dog lovers says that the tone of your voice is all that matters when communicating with your dog. You can say anything, and as long as you use a happy voice, your dog will understand that she or he has been a good dog.
In 2016, researchers from Budapest, Hungary put this hypothesis to the test by training 13 domestic dogs to sit in an fMRI scanner. The fMRI technique, short for functional magnetic resonance imaging, monitors brain activity by measuring changes in blood flow to different areas of the brain.
The researchers monitored the brain activity for the group of mostly border collies and golden retrievers as they heard typical words of approval as well as neutral words like conjunctions both in neutral and praiseful tones. According to their work published in the journal Science, when the dogs heard words of praise, in either tone of voice, activity was noted in the left side of the brain, suggesting that the left hemisphere in a dog’s brain processes language, just as in humans.
The tone of voice still mattered, however, because activity in the reward center, the area in the dog’s brain which processes positive feedback, not only registered when the dogs heard praise in a positive tone but also following neutrally spoken praise. So the dogs were able to process both the words being said and the tone in which they were stated. Attila Andics, one of the lead researchers on the study, summarized, “Dogs not only tell apart what we say and how we say it, but they can also combine the two for a correct interpretation of what those words really meant. This is very similar to what human brains do.”
The study is not able to confirm what meaning the dogs associate with each of the words they heard, but it does suggest that they are able to separate meaningful words (like those communicating praise) from words that don’t have any meaning for them. There’s no word on whether your dog will be happy to hear you call him “the dumbest dog ever” as long as you say it with a nice voice and a smile.
Can your dog remember what you do together?
In a separate study from the same institute in Hungary, researcher Claudia Fugazza conducted a study to determine whether or not dogs show signs of episodic memory, the ability to remember things they’ve done or seen in the past. We humans are obviously able to recall past events but scientists still debate whether or not nonhuman animals also have this skill when it comes to information not required for survival.
To test for episodic memory in dogs, their owners taught them a “do it” command which told the dogs to repeat an action, like jumping or touching an umbrella, after seeing their owner perform the action. Next, the owners trained their dogs to simply lie down after watching them perform the action. Finally, the owners threw in a twist. They performed an action so that their dog knew to lie down. Then, between one minute and one hour later, they commanded the dog to “do it.” So not only did the dogs have to remember what that action was, but they had to do it after not expecting their memory of the event to be tested.
The researchers found that in most cases, the dogs were able to recall the correct action, but that it was harder for them to remember the action after a longer delay if they weren’t expecting the memory test. The same is usually true for human memory and is why we make generally unreliable eye witnesses.
The results of the “do it” study suggest that dogs have something at least similar to episodic memory which suggests that “our dogs memories aren’t based simply on repetition and reward,” according to Brian Hare, a dog cognition expert at Duke University. This result could further mean that this type of memory did not evolve only in humans and primates.
Research from Emory University suggests that our dogs may in fact love us.
Does your dog love you or just your food?
So my dog may have a decent vocabulary and memory, but how much of this understanding extends to the abstract? Do dogs also have feelings and perhaps even love their owners back?
A research study led by neuroscientist Gregory Berns of Emory University suggests that our dogs may in fact love us, at least as much as they love food. Like the Hungarian studies, the dogs were trained to sit still for MRI scans and were never restrained so that they were free to leave the scanner at any time. The dogs wear ear muffs to protect their sensitive hearing and given chin rests to make them more comfortable (and to help keep them still).
The tests run by Berns and his group are not all that different from similar studies attempting to understand the response of the human brain. The dogs were provided rewards in the form of hot dogs and verbal praise while the scientists monitored their brain activity. They found that 20% of the dogs had a stronger positive response to praise than they did to food, suggesting that the connection they felt with their human companions was at least as important, if not more.
Other studies have suggested that dogs know how to read our facial expressions, communicate jealousy, show empathy, and even enjoy television programs. As a species dogs have been domesticated for as long as 10,000-30,000 years so it is possible that being around us has affected their evolution. If that is the case, then they may have affected our evolution as well.
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.
Image courtesy of shutterstock.
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