Research in recent years has shown that our brains can process the emotional content of vocalizations based on acoustic structure, and that various mammalian species share the same brain structures used for such interpretation. That means that we ought to be able to interpret the emotional nature of vocalizations from other species much like we understand those of other people.
Multiple studies of communication across species have found that animals can understand the emotional nature of vocalizations made by members of other species. In a number of studies, experience with the other species enhanced the ability to understand calls from that species.
Cross-species communication is particularly interesting between humans and dogs because of the long history we have of associating with one another, leading to the possibility that we have influenced each other’s vocalizations. In order to investigate people’s ability to understand canine growls, researchers conducted a study in which people listened to recordings of dogs growling and were then asked questions about the emotional state of the dogs.
In the study, “Dog growls express various contextual and affective content for human listeners”, 40 people heard recordings of growling dogs. All of the growls were recording in one of three contexts: guarding food from another dog, playing tug with a person and being approached by a stranger. In the first part of the experiment, the people were asked to rate each growl on a sliding scale for each of the following emotions: fear, aggression, despair, happiness and playfulness.
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The emotional profiles based on the 40 ratings of all three contexts were different. Food guarding had the highest aggression rating, followed by the stranger context, and the growls from play had the lowest aggression scores. For the other emotional states, the food guarding and stranger context did not differ from each other, but were rated higher in despair and fear than the playful growls and lower in playfulness and happiness than the growls recorded in play.
In the second test, people were asked in which of those three situations the growl was recorded. Overall, people correctly identified the context of 63% of the growls, which is significantly better than the 33% rate that chance predicts. The play growls were most readily identified, with 81% of them being correctly chosen. The food guarding growls were correctly identified 60% of the time, compared with 50% of the growls directed at strangers. Most of the errors in identifying these two (potentially aggressive) contexts involved confusion between the two of them, rather than with the playful context.
The authors conclude from this study that people can distinguish different types of dog growls, including being able to tell apart growls that are both in potentially aggressive contexts. Previous studies have found that people’s ability to understand canine growls is influenced by the time between growls and the duration of the growls. Based on analysis of the acoustic structure of the growls in this study, the key characters of the growls that make them seem different to people are the rhythm of the series of growls and the length of the individual growls within that sequence. Longer gaps between growls is associated with higher aggression scores. Shorter growls are generally perceived as more positive on emotional scales. In growls recorded in the context of a stranger approaching, the higher the pitch of the growl, the higher the fearfulness score.
Individual people varied in their ability to identify the context of the growls. Overall, women were better at it then men. Also dog guardians outperformed people who do not have dogs. Whether or not a person had ever been bitten by a dog had no effect on whether people were able to determine the context of a growl. This study shows that although people in general can interpret the emotion in canine growls, experience plays a role in how well they are able to do so.
Can tell what your dog’s growls mean?