Study Finds That Dogs Can Have Upsetting Reactions to Humans Crying

There is no dog owner out there who hasn’t wondered at one point in time: “Can my dog understand my emotions?” While this question has been around for ages, the latest scientific studies reveal that your pet dog can get stressed out when you are sad and cry.

The study included both dogs and pet pigs, both of whom were discovered to be able to tell the difference between humans humming and vocally crying. The dogs especially were seen to get more stressed out by the crying, more so than the pigs, according to a new scientific paper in the journal Animal Behavior.

This is a breakthrough study, indicating that during the early domestication process, dogs evolved specifically to have a greater understanding of human emotions. Previously, it was also found that dogs were capable of something called “emotional contagion”, meaning that they align their emotional states with that of their owners.  

"We were curious whether the emotional contagion observed between dogs and humans was related to the well-conserved acoustic structure of some emotional vocalizations across species, or if it was promoted by the dogs' specific selection for cooperation and dependency on humans," study author Fanni Lehoczki, an animal behavior researcher at Eötvös Loránd University in Hungary, said in a statement.

To investigate if the stress responses were universal across intelligent pet animals or specific to just domesticated dogs, the research team compared the reactions of both companion pigs and pet dogs to the sounds of humans either humming or crying. The humming sounds were non-negative but still strange sounds while crying was distinctly emotionally negative.

"For collecting this data we used a so-called 'citizen science approach'," co-author Paula Pérez Fraga, also a researcher at Eötvös Loránd University, added. "The animals were tested remotely at their homes by their owners, facilitating the inclusion of more subjects in the study from various locations worldwide."

Interestingly, it was revealed that the pigs were much more stressed when hearing the humming, while dogs reacted stressed to the sound of humans crying.

"Our study revealed a remarkable difference between dogs' and pigs' reactions to human sounds: dogs exhibited more stress responses and vocalizations to the crying, whereas pigs exhibited fewer stress responses and vocalizations to the crying," it was announced in the study. "To our knowledge, this is the first study comparing the behavioral reactions to human emotional vocalizations of two social domestic species kept as companion animals."

The reason for this could be that dogs were domesticated over thousands of years, and there was a strong “selection pressure” for them to cooperate with humans and understand their emotions. And the fact that the dogs were stressed by the sounds of humans crying, definitely indicates that they have the so-called “emotional contagion” from humans. 

"While we cannot exclude that pigs also experienced emotional contagion when listening to human crying, one explanation for their reaction might be that humming is highly unusual and surprising sounds stress out pigs more than human sadness. On the other hand, one thing is clear, dogs seem to be specially keen on catching the emotional content of differently valenced human vocalizations, even of the more unusual ones," Pérez Fraga added. "Therefore, selection for cooperation with humans might be key in promoting human-sound induced emotional contagion in domestic animals. However, to confirm this suggestion further research is needed involving physiological measurements."