Data from: Dogs recognize dog and human emotions

The perception of emotional expressions allows animals to evaluate the
social intentions and motivations of each other. This usually takes place
within species; however, in the case of domestic dogs, it might be
advantageous to recognize the emotions of humans as well as other dogs. In
this sense, the combination of visual and auditory cues to categorize
others' emotions facilitates the information processing and indicates
high-level cognitive representations. Using a cross-modal preferential
looking paradigm, we presented dogs with either human or dog faces with
different emotional valences (happy/playful versus angry/aggressive)
paired with a single vocalization from the same individual with either a
positive or negative valence or Brownian noise. Dogs looked significantly
longer at the face whose expression was congruent to the valence of
vocalization, for both conspecifics and heterospecifics, an ability
previously known only in humans. These results demonstrate that dogs can
extract and integrate bimodal sensory emotional information, and
discriminate between positive and negative emotions from both humans and
dogs.