Horses form cross-modal representations of adults and children

Emotional contagion of fear and joy from humans to horses using a combination of facial and vocal cues

Emotional contagion, the emotional state-matching of two individuals, has been documented in various species. Recent findings suggest emotional contagion could also take place between humans and domestic mammals. However, the range of targeted animal species and human emotions that have been studied is still limited, and the methodology to investigate emotional contagion in this context is not fully established. This study examined emotional contagion of fear and joy from humans to horses by measuring physiological (heart rate, infrared thermography) and behavioral responses (posture, laterality bias, facial expressions) to videos of human fear, joy, or neutral emotions. Horses (n = 45) exhibited higher heart rates and ear movements during the fear and joy videos compared to the neutral ones, suggesting heightened arousal. During fear videos, they showed a greater increase in eye temperature than during joy or neutral videos, and maintained an alert posture for longer than during neutral videos, expressing specific facial expressions including inner brow raising and blowing. During joy videos, they showed a higher right eye preference (indicating a higher left-hemisphere bias) than during neutral videos, suggesting a more positive emotional valence. These findings suggest that human facial and vocal cues of fear and joy trigger emotional contagion in horses, which may influence the human-horse relationship.

Horses discriminate between human facial and vocal expressions of sadness and joy

Communication of emotions plays a key role in intraspecific social interactions and likely in interspecific interactions. Several studies have shown that animals perceive human joy and anger, but few studies have examined other human emotions, such as sadness. In this study, we conducted a cross-modal experiment, in which we showed 28 horses two soundless videos simultaneously, one showing a sad, and one a joyful human face. These were accompanied by either a sad or joyful voice. The number of horses whose first look to the video that was incongruent with the voice was longer than their first look to the congruent video was higher than chance, suggesting that horses could form cross-modal representations of human joy and sadness. Moreover, horses were more attentive to the videos of joy and looked at them for longer, more frequently, and more rapidly than the videos of sadness. Their heart rates tended to increase when they heard joy and to decrease when they heard sadness. These results show that horses are able to discriminate facial and vocal expressions of joy and sadness and may form cross-modal representations of these emotions; they also are more attracted to joyful faces than to sad faces and seem to be more aroused by a joyful voice than a sad voice. Further studies are needed to better understand how horses perceive the range of human emotions, and we propose that future experiments include neutral stimuli as well as emotions with different arousal levels but a same valence.

Garrano Horses Perceive Letters of the Alphabet on a Touchscreen System: A Pilot Study

This study aimed to use a computer-controlled touchscreen system to examine visual discrimination in Garrano horses (Equus caballus), an endangered breed of pony belonging to the Iberian horse family. This pilot study focused on the perceptual similarity among letters of the alphabet. We tested five horses in a one-male unit (OMU) living permanently in a semi-free enclosure near their natural habitat in Serra d'Arga, northern Portugal. Horses were trained to nose-touch black circles that appeared on the screen. Then, they were tested for discrimination of five letters of the Latin alphabet in Arial font, namely O, B, V, Z, and X, using a two-choice discrimination task. The confusion matrix of letter pairs was used to show the MDS and to identify the relative contribution of shape features. The results showed perceptual similarities among letters with curvatures pitted against those of straight lines. Shape perception in horses seems to share features with that of humans and other animals living in different niches. The touchscreen system proved to be an objective and innovative way of studying cognition in the socially organized group of horses. The automated system can promote the welfare of captive horses by maximizing their freedom of movement.