Category-dependent contribution of dog facial and bodily cues in human perception of dog emotions

The increasing popularity of human-dog interaction in our society calls for fuller understanding of humans’ ability to appraise dogs’ affective states, yet most research only focuses on recognizing dog facial expressions of primary/basic emotions. While the face is the dominant human emotional expression channel, bodily cues are also informative indicators of dog emotional states. In this online study, with dynamic and naturalistic videos depicting a common range of dog primary (anger, disgust, fear, happiness, sadness, surprise) and secondary emotions (appeasement, frustration, pain, positive anticipation, separation-distress), we compared human performance from 447 participants in categorizing dog facial expressions (with a visible dog face only) and bodily expressions (with a visible dog face and body). The analysis revealed when averaging across all tested emotions, bodily expression tended to attract higher categorization accuracy than facial expression. However, the two expression channels demonstrated category-dependent modification of dog emotion categorization accuracy (e.g., higher accuracy in recognizing facial expressions of anger and surprise, but bodily expressions of happiness and fear) and bias (e.g., mistaking fear facial expression as happiness, but fear bodily expression as sadness). Furthermore, the impact of owner experience on recognizing dog emotions was also modulated by the expression channel and emotion category (e.g., prolonged experience with dogs tended to improve performance in recognizing the fear facial expression, and the appeasement bodily expression). Taken together, these results suggest that different channels of emotional expression by dogs may transmit category-specific diagnostic emotional cues, which aid human appraisal of their affective states.