Classifying dogs' (Canis familiaris) facial expressions from photographs.

Humans accurately read other humans' emotional facial expressions. Little research was found examining human ability to read dogs' expressions. Cross-species research extended facial expression research to chimpanzees, and there is much research on dogs' auditory signaling to humans. To explore humans' ability to identify dogs' facial displays, photographs of a dog's face were taken under behaviorally defined conditions expected to elicit specific emotions. Dog experts consistently rated these photographs. The photographs rated as best by experts were used as stimuli for people experienced and inexperienced with dogs. Both groups were able to read the dog's emotions. Paradoxically, experienced people were less accurate reading aggressiveness. Experienced people were better identifying behaviorally defined situations. Research using behaviorally anchored, standardized photographs is recommended.