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It may not be Dr. Dolittle-style animal communication, but researchers have found that humans are able to glean information about the feelings of creatures including pigs, horses and goats based on their vocalizations.
The team says the findings suggest that some information within sounds, such as the intensity of an animal’s emotions, appear to be transmitted similarly across species.
“[People] they probably base their decisions on their knowledge of what humans sound like when they are more or less excited…because arousal, which is linked to stress pathways, is a system that is well conserved among vertebrates,” said the Dr Elodie Briefer, co-author of the University of Copenhagen research.
They also looked into whether people could determine whether an animal was expressing a positive or negative emotion.
“We can’t really rely on what we know from humans because it varies so much between species — there are a lot of differences in how species express emotions, even closely related ones,” Briefer said.
Writing in the Royal Society Open Science journal, Briefer and colleagues report how they recorded vocalizations from six animal species: horses, pigs, goats, cattle, Przewalski’s horses (wild horses) and wild boars. The team noted whether the sound was emitted when the animal was excited, as determined by an elevated heart rate or movement, and whether the sound was emitted in a positive context, such as anticipation of food, or in a negative context, such as isolation.
For humans, the team used existing recordings of meaningless strings of speech spoken in anger or fear to represent higher and lower emotional intensity – or excitement – respectively, and in an angry or joyful manner to suggest a negative or positive context. .
The researchers then asked 1,024 participants from 48 countries to listen to sound pairs online.
For each species, participants were given four pairs of vocalizations. For two pairs they were asked to rate the emotional intensity of the sound as high or low, while for the other two pairs they were asked to rate the emotion as positive or negative.
The results reveal that, overall, participants correctly rated the subject’s emotional intensity 54.1% of the time and the type of emotion 55.3% of the time.
However, when the team analyzed the data further, they found that the participants did just better than chance on both metrics when they rated the vocalizations of pigs, horses, goats, humans and, by emotion type only, boars.
“People are generally better at recognizing domesticated species than wild ones,” Briefer said.
The level of arousal of pigs and horses was correctly assessed 59% and 58% of the time, respectively, compared to 55% of humans, while their type of emotion was correctly assessed 58% and 64% of the time, respectively. times, compared to 68% of humans.
“We’re pretty confident that when it’s higher than chance it’s definitely higher than chance,” Briefer said, adding that while the ratings may have been high for horses because many participants reported contact with such animals, the success rate relatively low for most species, including humans, could be due either to the brevity of the recordings or to the use of the same type of sound for each pair of vocalizations, such as mooing for cows or neighing for horses.
The shorter participants’ success in rating the type of emotions varied much more than their ability to determine the intensity of the emotions.
“If we take it to the next level, we can very likely easily train people to recognize sounds,” he said, noting that it could help those who work closely with animals — from farmers to pet owners — better understand them.
“In the past, scientists focused on physical health to assess animal welfare. Nowadays, most of us recognize the great role emotions play.