Polls show 65-95% of people admit to regularly talking to their pets. And sometimes it really seems like they understand us. It’s pretty clear that they know what we mean when we say W-A-L-K or T-R-E-A-T! But do they really get more than that? How many words can they learn? Do they just know the names for things, or can they follow more complex phrases or even sentences?
It is surprisingly difficult to clearly answer these questions. Dogs are exceptionally good at understanding humans; better than any animal outside our own species. But when we talk to them, we give a lot of information besides just words. Our gestures, facial expressions, posture, tone, and many other elements of our behavior carry meaning for our canine companions, and it is difficult to separate this from what they might understand from out words alone.
Some studies have tried to do this, and the results are impressive. Most dogs living in a home with humans probably understand 70-80 words that are regularly directed at them. They most commonly know their name, the names of toys and other valued objects, regular commands, and words for other things of special significance, like “walk” and “park.”
Some dogs with extensive training can do a lot more. A border collie named Chaser was shown to understand over 1,000 words, and to be able to understand new combinations of these words. For example, once taught that “touch” means to touch an object with her nose, she could direct this behavior at objects she had never touched before once she knew what the object is called. Importantly, she could do this based on spoken words only, without being able to see the human giving the commands, which reduces the chance that she might have been responding to other cues. This is an impressive level of comprehension that takes even human children more than a year of growth and development to begin mastering!
Of course, language doesn’t come as naturally to dogs as humans, and they certainly don’t ever approach our level of comprehension. The average human without any special training routinely uses about 20,000 words and can comprehend more than 40,000, and we use language in incredibly complex and creative ways. So your dog may not really get the nuances when you tell her about your recent breakup or your tough day at work. But fortunately, she’ll listen and support you anyway, because dogs are awesome!
For a closer look at some studies of what dogs can do with human language, check out these articles.
Catherine Reeve, Sophie Jacques. Responses to spoken words by domestic dogs: A new instrument for use with dog owners. Applied Animal Behaviour Science. Volume 246, 2022, https://doi.org/10.1016/j.applanim.2021.105513
John W. Pilley, Alliston K. Reid. Border collie comprehends object names as verbal referents. Behavioural Processes. Volume 86, Issue 2, 2011. https://doi.org/10.1016/j.beproc.2010.11.007.
(discussed briefly in this USA Today article or in depth in this book)