In the study, published in the December issue of Current Biology, researchers used 250 dogs' head-tilting behavior to see how much the pooches were able to comprehend and in which hemisphere of their brains that processing might be happening. Each dog was positioned in between two speakers, with a handler just behind it and an experimenter in front. When the dog was calm and facing forward, the experimenter cued a sound. Sounds included tones and speech that differed in intonation, content, and language.
The results showed that the dogs turned in different directions when hearing different sorts of cues, indicating that their brains were processing these sounds in different ways. When the sound only contained emotional cues, such as an encouraging-sounding tone, the pups turned to the left. But, when the cue contained a meaningful word (e.g., a familiar command delivered in a monotone voice), the dogs were more likely to turn to their right. Because these kinds of sound cues are processed by the opposite brain hemisphere, this means the left side of their brain was working this sound out. And, humans sometimes show a remarkably similar pattern of brain activity when listening to verbal cues.
So, these results suggest that dogs do understand our commands — perhaps a little more than we give them credit for — and they process those phrases similarly to the way we process language. However, understanding us is one thing. Whether or not our doggies care to comply with those commands is a completely different issue. We know our cats definitely don't.