Surprisingly, a dogs muzzle may be blocking his view of some of our faces
I have fond memories of my Beagle, Darby, coming into the kitchen when I was preparing dinner. I would casually chat with him, and when I would turn to him to say something he would cock his head to the side in a most endearing manner. Many people report that when they are speaking to their dog their pet often tilts its head to the side, and some have asked me about why that happens.
Unfortunately, up to now, there is not been much research on this issue, although there has been some speculation. Some people have suggested that dogs tilt their heads to the side when we speak to them so that one ear can hear more clearly what we are saying. Others have suggested that it is a social signal—perhaps the dog recognizes that we respond to that particular posture in a positive way (because it is so cute) and therefore the dog adopts this position because they are more likely to get smiles and rewards when they do.
I suppose it is because I worked and did research in the area of sensory perception for many years that it dawned upon me that the reason some dogs tilt their heads when we are speaking to them has to do more with vision, rather than hearing and social endearment. Try the following simple experiment; hold your fist up to your nose as in the figure here. Now, in effect, you are viewing the world with a head shape that has a muzzle like that of a dog. If you now look at a person's face you will find that the muzzle will block some of your vision, and reduce your ability to see the lower part of the face. Remember it is this part of the face, particularly the mouth region, which is a vital component of human emotional expressions. Next, still with your muzzle in place, tilt your head when you are looking at the face. With this head posture you can now clearly see the mouth region.
We know that dogs continually scan our faces for information and to read our emotional state. Hence it is likely that one reason why dogs may tilt their heads when we talk to them is because they want to see our faces better, and to compensate for the way in which their muzzles obscure part of their vision.
Of course this idea was simply speculation, and no data were available. However it suddenly dawned upon me that there was an easy way to at least get a bit of data to confirm or disprove this hypothesis. Some dogs have flatter faces. Technically they are said to have brachycephalic heads. These would include dogs like Pugs, Boston Terriers and Pekingese. With a less prominent muzzle extension, there should be a reduced amount of visual obstruction, and these dogs would need to tilt their head less. To see if this was the case I conducted a survey on the Internet.
The survey was very brief, and people simply had to answer how often their dog tilted their heads when they were speaking to them, using a scale which ran: never, seldom, occasionally, frequently, most of the time, or always. When I scored the data I combined the responses of frequently, most of the time, and always, an indication of "head tilting dogs". I also asked the people who responded to tell me for the breed of their dog, and for people with mixed breeds to select the approximate head shape of their dog from a set of six photos.
I got a very good response to this survey since 582 people completed it. Of these, 62% reported that their dogs frequently to always tilted their heads when they spoke to them. In the overall sample 186 people had dogs with the flatter brachycephalicheads. When we divide the group into those dogs with the more pronounced muzzles (technically those dogs with longer narrower heads like collies or greyhounds are doclichocephalic, while those with a wider intermediate length muzzles, like retrievers or beagles are called mesaticephalic) versus those with the flatter faces, we do get a difference in the frequency of head tilting. 71% of the owners of the dogs with the larger muzzles report that their dogs often tilt their heads when spoken to. On the other hand only 52% of the owners of the flatter faced, brachycephalic dogs reported that their dogs often tilted their heads when spoken to. This is a statistically significant difference that clearly suggests that head shape, and size of the muzzle does influence head tilting in dogs.
Now, of course, 52% of head tilting in the brachycephalic pets is still a large number of dogs, and it may be that even the flatter muzzles do obscure the dog's vision to some degree. If so, these dogs can still benefit visually from tilting their heads. However it is more likely that the fact that a dog's muzzle blocks their vision of the lower part of the human faces that they are trying to look at is just one of the factors that cause dogs to tilt their heads when we talk to them. Perhaps something to do with hearing plays a role, or perhaps the dogs are really just trying to look cute. Nonetheless this study is a first step toward finding the answer, and at least we now have a bit of data to work with.