Hiiiiiiieeee! Who’s a little sweetie? You, yes, you are!

Sound familiar? Even if you yourself have never talked this way to anyone, you’ve probably heard someone do it. But if you try to picture who’s on the receiving end of this interaction, is it a baby or is it a dog?

It could be either one. Linguists have studied the characteristics of the way people talk to babies and to pets and found a great deal of overlap. The features of both infant-directed speech (also known as motherese) and pet-directed speech include swooping intonation contours, higher pitch, and slow articulation.

Why do people use these features? In the case of infant-directed speech, researchers believe they may be useful for encouraging language development in the child by highlighting important contrasts between sounds and holding attention. Our impulse to speak this way to babies may have a biological basis stemming from an evolutionary advantage for behaviors that promote language acquisition. However, not all cultures use this type of infant-directed speech, and babies in cultures without it do still learn language. Humans learn language whether or not anyone talks to them in a sing-song, high-pitched tone.

So baby talk might not actually help babies learn to talk. But when babies do start to talk, using words and sentences, caregivers begin to drop the exaggerated tone. The adult tendency to sing-song seems to be triggered not so much by the urge to instruct, but by the perception that the person we’re talking to doesn’t know our language.

The perception seems to underlie why we also talk to dogs in this voice. We know they’re not going to learn to talk, but we can’t help going into baby talk mode. And since, while they can learn to understand various things, they never start using words and sentences, our baby talk habits persist.

A recent study by Tobey Ben-Aderet and colleagues, published in the Proceedings of the Royal Society B, found that people use high-pitched, dog-directed speech patterns even while reading sentences to pictures of dogs. While the features were a bit more exaggerated for pictures of puppies than for adult dogs, they were used across the age range. It was not a response to “babyness,” per se.

They then played the recorded sentences to dogs over a speaker and recorded their reactions. While puppies did respond more strongly to dog-directed speech patterns, adult dogs showed no preference for it. This may be because adult dogs are more responsive to people they know, and the recorded speakers were unfamiliar, but it may also suggest, according to the report, "that pet-directed speech exploits perceptual biases which are present in puppies but not in adult dogs.” Baby talk may be somehow functionally useful, but only for puppies.

Usefulness isn’t everything, though. The authors conclude:

"This study suggests that dogs may appear as mostly non-verbal companions to humans who consequently modify their speech features as they do when speaking to young infants. Such a speaking strategy seems to be employed in other contexts where the speaker feels, consciously or unconsciously, that the listener may not fully master language or has difficulty in speech intelligibility, such as during interactions with elderly people, or when speaking to a linguistic foreigner."

We don’t talk to dogs like babies because we see them as babies, or even necessarily because they're cute, but because we see them as having a harder time understanding us. Dog-directed speech features may actually help them understand us, but even if it doesn't, we'll probably keep on using it. Won't we! Won't we, baby! Yes, we will! We will! MWAH!