Dog owners often say they “know” that their dog understands what they’re feeling. Now, scientists have the evidence to back this up. Researchers tested 17 adult dogs of various breeds to see whether they could recognize emotional expressions in the faces and voices of humans and other dogs—an ability that’s considered a higher cognitive talent because two different senses are involved. Each dog took part in two test sessions with 10 trials. One by one, they stood facing two screens on which the researchers projected photos of unfamiliar but happy/playful human or dog faces versus the same faces with angry/aggressive expressions (as in the photo above). At the same time, the scientists played a single vocalization—either a dog bark, or an unfamiliar human speaking in Portuguese, a language none of the dogs had previously heard, or a neutral sound. The dogs looked much longer at a face (dog or human) when the expression matched the tone of the voice, a measure that’s also been used to assess various cognitive abilities of other mammals, the scientists report online today in Biology Letters. The dogs were best at this when looking at a fellow dog, which supports another study showing that dogs preferred looking at images of other dogs rather than those of humans. It’s the first time that a species, other than humans, has been shown to be capable of interpreting the vocal and facial expressions of an entirely different species of animal—a talent that surely helps Fido survive in its ecological niche: the jungle of the human home.