I'm Craig and this is Mental Floss on YouTube and today I'm going to be answering the big question: 

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Most experts believe that head-tilting is a method of sound localization. Basically, some sound waves are easier to understand than others. It's especially hard for us to understand a sound if we don't know where it came from and when we tilt our heads that actually changes how the sound waves amplitude and phase hit our ear. Is someone snacking on something? I think I hear someone snacking on something.

We're making it so that the sound wave can reach our ear in a more horizontal way than it otherwise would. It's also possible that it is now a deep, in-built reaction to be confused about things in general.

As for why we tilt our heads when asking a question, that's a little trickier. It has definitely become a standard part of our body-language, but there is maybe more to it than that.  Like, tilting your head might also make you seem more likable, rather than just talking like this all the time and staring at someone and not moving your head at all.

A head tilt leaves a carotid artery on your neck vulnerable, so it sends a message to the other person that you don't consider them a threat, and they're not gonna get all stabby on your carotid artery, and according to social psychologist Dacher Keltner, "In the primate world, tender warmth is signaled by head tilts."  Few studies have shown that people are perceived as more attractive while tilting their heads.  Women are considered more attractive while tilting their heads slightly forward, and men are viewed as more masculine while tilting their head back a little.  'Sup, bro? 

Dan also asks why animals seem to tilt their heads in the same way as people.  This is most commonly observed in dogs.  Of course, we can't know exactly why a dog does this, because if we ask a dog, it's just gonna tilt its head.  Dr. Stanley Coren studied this phenomenon in 2013 by surveying 582 dog owners.  He found that 71% of owners of dogs with large muzzles reported that their dogs frequently tilted their heads while being spoken to, and dogs with flatter faces like pugs and Boston terriers had owners who only reported it around 52% of the time.

So Coren believes that dogs are trying to prevent visual obstruction, they're attempting to read the emotion of the person who's talking, so they tilt their heads to be able to see over their muzzle.  Of course, since 52% of dogs with flat faces also did this, there are probably other factors at play, like hearing.

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