Understanding social communication between humans and dogs

This research investigates social communication between humans and dogs. Chapter 1 outlines the current understanding of dog social communication, highlighting outstanding questions with regards to the production and perception of speech to dogs, and the function of barking in domesticated dogs. The first study investigated individual differences in the production of a special speech type known as dog-directed speech (DDS), which is higher in pitch, pitch modulation, and affect compared with adult-directed speech (ADS). Results showed that females increase their pitch more than males in DDS, but that the difference in pitch modulation and content of speech between ADS and DDS does not differ between males and females. Neither experience with dogs, nor levels of empathy influenced production of DDS. The second study used playback experiments to investigate whether dogs prefer DDS compared to ADS and found that dogs display an attentive and social preference for DDS, but only when both content, and prosody of speech are dog-directed. This demonstrated for the first time that naturalistic DDS may function to improve the affiliative bond between humans and dogs. The third study found that direct eye-gaze selectively enhances the preference for DDS, suggesting that both speech type, and eye-gaze are important cues for communication with dogs. Finally, I examined whether dogs understand contextual information conveyed by conspecific barks. Findings suggest that dogs do not use contextual information in conspecific barks to inform their behaviour in a naturalistic setting and that humans are more sensitive to these cues than dogs. This suggests that increased barking in domestic dogs may have evolved as a means of communicating with humans, rather than conspecifics. Overall, this research demonstrates the complexity of dog-human communication and highlights the value of comparative research for gaining insight into the evolution of sophisticated social communication resulting from both natural and human selection.