Dogs have a stupendous ability to sense our emotions through our facial expressions. They even follow our hand gestures. They seem to know exactly when we need their loving presence and stick close to us. But we do not know much about how their hearing plays a role in gauging our emotions.
A recent research done by the Department of Veterinary Medicine at the Bari Aldo Moro University, in southern Italy studied how dogs analyse human emotions based only on our vocalisations. Previous research has shown that dogs combine hearing and sight to match angry and happy human faces with happy and sad vocalisations.
While using only their hearing ability, researchers found that dogs know the difference between a positive laughing sound and the negative crying sound. They also found that dogs get upset when they listen to negative sounds more than when they hear positive sounds.
There are basically six emotions that humans recognise from vocalisations which are fear, anger, sadness, disgust, surprise and happiness. The study aimed to determine if dogs can recognise all the six emotions through just non-verbal vocalisations.
30 dogs were given food in a bowl at the center of a testing room and two speakers were evenly placed at either side of their bowl. While the dogs ate, non-verbal sounds were played on the speakers. For instance, fear sounds were screams and happy sounds were giggles or laughs. The dog’s reaction to each of the sounds were videotaped.
The scientists wanted to find out if the dogs turned their heads to the right speaker or the left, although the two speakers played the same sound. It was important for two reasons. Firstly, just like humans, dogs use the left part of their brain to control the right side of their body and the right part of the brain to control the left side of their body. Secondly, previous research showed the fact that dogs process emotionally positive sounds with the left side of their brain and emotionally negative sounds with the right side of their brain. So, if a dog turned left after hearing a sound it means that they were analysing the sound with the right side of their brain. Which means that they have interpreted the sound as negative.
Results further stated that dogs turned to the left when they heard fear and sad vocalisations. They showed the same for anger as well. This means that they were processing these sounds on the right side of their brain which has been associated with negative emotions. When happy sounds were played, the dogs turned to the right and it was processed in the left side of their brain that has been associated with positive emotions.
Disgust and surprise did not show much of significant trends as those emotions were more dependent on the context. For example, poop may be disgusting to us but it is exciting for dogs. So, they would not know how to interpret the vocalisations of disgust and surprise without more detailed information.
To sum it all, dogs can determine human emotions by using their ears, at least for emotions like happiness, sadness and fear. The use the right side of their brain for processing negative emotions and left side for positive emotions. Additional information that was collected like their heart rate, tail wagging and yawning further supported these above mentioned findings. This definitely gives us more insight about animal emotions. As we cannot ask a dog how they feel in a situation, but with the help of these methods we are able to determine if dogs are able to determine if the feelings are positive or negative!