RCA Victor successfully bred this trait into all domestic canines.
Only tangentially related: http://www.youtube.com/watch?v=9uuqXXT7VYo
Geez – have any of you people even owned a dog?
Our dog never cocked his head like that when anyone talked to him. He cocked his head when confronted with something unusual or novel. It seems pretty clear to me that it;s a physical manifestation of “Huh? What’s going on? I don’t understand this.” from the dog. He did it plenty of times when there was no sound to confuse him at all – just visual input.
So if your dog is cocking his head when you talk, it’s evidently a sign that he doesn’t understand.
I’ve always taken Nipper and the Gramophone (the symbol of RCA Victor in the US, and HMV in the UK) to be cocking his head because he hears His Master’s Voice coming from the strange box, but his Master is nowhere to be seen. It’s clearly a “Huh? What’s Going On?” gesture, not a “Someone’s Talking to Me” gesture. Moreover, the fact that this image was widely used is evidence that most people understand the significance of the cocked head.
Google “dog cocked head confused” and you’ll get plenty of cites. One site at least claims that the purpose is to hear the sound better and/or where it’s coming from. But, as I say, I’ve seen dogs do this when there was no sound at all, so I don’t buy it.
Yup, two of 'em at present. Both cock their heads when I talk to them. So there goes your theory!
I know exactly why they do it. It’s an integral part of pug-human mind control. They realize that cocking their heads puts them in cute overload mode, and therefore the mind control waves work more efficiently, making toys get thrown, bellies get rubbed, and snacks get offered. I’m surprised the other breeds haven’t picked up on it yet.
Like heck! It’s not theory – I’ve never seen a dog cock its head merely from being spoken to. And I’ve seen them cock their heads plenty of times without any aural stimulation. Not theory, just observation.
Mine do exactly that. Heck, if I play that video while they’re in the room, they do the head tilt.
Maybe it’s a pug thing.
Oops, I see that video was already linked. Sorry for the double link! Shoulda read the whole thread before posting!
In my dog’s case it’s because he thinks he may have heard me say either “walk” or “treat” and he is now paying attention in the hope that one of those words may come up again.
Dogs’ ears are not like our ears. The fuzzy floppy bits on the outside don’t give you much indication. From what I’ve read (about pugs in particular), their ear canals are quite long, which means that the parts that they actually hear with, the eardrum and such, are located very low, almost in their neck. The head-cocking is an attempt to orient those hearing parts to hear you better.
I tend to agree with **CalMeacham **. I’ve had many a dog tilt it’s head when I talk to it, but mostly when the words are unfamiliar. I think it’s a combination of interest and trying to comprehend.
A treasured poetic memory of mine was my little dog sitting in the kitchen staring at her water bowl with her head tilted and I swear an eyebrow raised. A wee mouse had evidently gotten into her bowl and no doubt spent the evening scrambling up the sloped side and sliding back down. Finally exhausted the mouse drowned in the inch of water at the bottom of the bowl. I have no doubt my dog was saying, "WTF?"and wondering whether it was a snack.
Here’s a really extreme example – I thought this girl was going to hurt herself!
In my experience, mine tilt their heads when I make novel noises and don’t bother during instructions they’ve heard before.
Seeing as pugs are only slightly more intelligent than animate mushrooms, I don’t think these two viewpoints are at odds. Pugs confuse easily! 
(And I say this as a former owner and adorer of pugs; I love the stupid little mushrooms!)
Dogs cocking their heads is nothing to fret about.
When the dog progresses to cocking her gun, now that’s something to worry about.
My dog cocks his head when he hears familiar words, particularly his favorites: “walk,” “dinner,” and especially “cookie.” If I repeat the word, he’ll try to cock it further, which looks really funny.
I believe that it’s natural for dogs and many other animals to try to change their perspective when confronted with critical stimuli. An unfamiliar object (that may be dangerous or rewarding), a distant sound (likewise), and, in the case of dogs, words that lead to good things. There’s also the training factor, as dogs do get rewarded for it, 'cause it’s cute, but there is a proven benefit in the wild. Moving the ears into different planes helps locate the source of a sound – some owls have their ears located at different heights, apparently for exactly this reason: Sound localization - Wikipedia
This makes sense. It would also explain why, when I talk to my cat, she glares at me like I’m scum and walks off in the middle of a sentence. 
For the win!!!
My brother’s dog used to cock his head and peer at us when we were talking to him, but more so when he was sitting down.
Once, in the car, the radio started playing “Jungle Love” by the Steve Miller band. There’s a loud, synth sound at the very start of it that caused the dog to tip his head so far to the left that he was practically looking at the radio sideways.
Because they can. Wait, no, that’s something else.