The international research team from France’s National Research Institute for Agriculture, Food and Environment INRAE, France’s University of Tours, and the Finland’s University of Turku observed and analyzed horses’ behavior when shown human faces and voices expressing joy or sadness. During the experiment, the horses’ heart rates were also recorded.

“Sadness is a particularly interesting emotion, because it is not only of negative valence—contrary to joy, which is positive—but it is also of low arousal. Previous studies have shown that horses react to high-arousal emotions like anger or joy. Could they also detect signals of sadness, a low-arousal emotion?

“We wanted to study whether horses can associate the vocal and facial signals of human sadness, as they can for joy and anger,” says Plotine Jardat, Doctoral Researcher from the French National Institute for Agriculture, Food and the Environment and the University of Tours, France, and the lead author of the study published in Animal Cognition.

Horses’ Emotional Intelligence: Decoding Human Faces and Voices

During the experiment, the horses were placed in front of two screens that displayed two faces of the same person, one expressing joy and the other expressing despair. A voice was transmitted simultaneously, conveying either joy or grief.

The horses’ first glance suggested that they matched the expression and voice of sadness or gladness. The researchers discovered that during the horses’ initial glances at each image, a bigger proportion of the horses looked at the unmatching image than the image that matched the sound.

In other words, when the horses first saw the photos, they were taken aback by the incompatibility of the sad face with the joyous voice, and vice versa. This implies that horses can recognize a human face and voice conveying the same emotion, whether sad or joyful.

“This is interesting because it would mean that when horses observe our faces and hear our voices, they don’t just see and hear separate things, but they can match them across different modalities. You could imagine that they have a particular box in their mind labeled ‘human sadness’ containing the characteristics of both a human sad face and a human sad voice,” says Doctoral Researcher Océane Liehrmann from the University of Turku.

The team has utilized a similar arrangement in several earlier investigations. Its goal is to investigate the animals’ cerebral processing of visuals and noises, as well as their congruence. The horses reacted to the setting in prior trials on anger and delight, as well as on the perception of adults and children, by looking more at the image that did not match the sound. The researchers believe that horses are drawn to the incongruent visual because of the absence of correlation between it and what they hear.

Horses Respond to Human Joy and Sadness Through Faces and Voices

The researchers also noticed that following the initial look, horses focused on the screen with a pleased face and gazed at it for a longer period and a greater number of times. Furthermore, when the transmitted voice indicated joy rather than grief, their heart rates tended to climb more, indicating that the horses were in a higher arousal state while hearing the former.

Three possibilities, according to the researchers, could explain these findings. First, the horses may have been more drawn to the joyous visuals due to increased movement, and more aroused by the joyful sounds due to acoustic qualities such as pitch fluctuations. Second, horses may have associated human joyous faces with positive experiences, so they prefer to look at expressions related to positive memories. Third, horses may feel more positive when they see images of joy and become more stimulated when they hear joyous voices, due to a process known as “emotional contagion.”

Emotional contagion is the connection of an observer’s emotional state with the emotional condition of the individual being observed. It has been observed in humans and monkeys, and various studies have suggested that it may also occur between humans and other animals, such as horses. This phenomenon is sometimes seen as a foundation for empathy.

“Overall, our study shows that horses can differentiate audible and visual signals of human joy and sadness, and associate the corresponding vocal and facial expressions. Horses were also more attracted and seemed more animated by joyful expressions, so people who interact with horses could benefit from expressing joy during these interactions,” Jardat concludes.

The researchers emphasize that further research is needed to better understand horses’ perceptions of human melancholy. In the future, researchers hope to learn whether horses can distinguish melancholy from other unpleasant emotions, or whether human sad expressions might influence horses’ behavior, particularly during human-horse interactions.

Reference :

1. Horses discriminate between human facial and vocal expressions of sadness and joy – (https:pubmed.ncbi.nlm.nih.gov/37543956/)

Source: Medindia