Are Horses (Equus caballus) Sensitive to Human Emotional Cues? - PubMed (original) (raw)

Are Horses (Equus caballus) Sensitive to Human Emotional Cues?

Chihiro Baba et al. Animals (Basel). 2019.

Abstract

Emotions are important for social animals because animals' emotions function as beneficial cues to identify valuable resources such as food or to avoid danger by providing environmental information. Emotions also enable animals to predict individuals' behavior and determine how to behave in a specific context. Recently, several studies have reported that dogs are highly sensitive to not only conspecific but also human emotional cues. These studies suggest that domestication may have affected such sensitivity. However, there are still few studies that examine whether other domesticated animals, in addition to dogs, exhibit sensitivity to human emotional cues. In this study, we used a gaze-following task to investigate whether horses (Equus caballus) are sensitive to human emotional cues (happy, neutral, disgust) and if they adjust their behavior accordingly. In the study, the experimenter suddenly turned her head to either right or left and showed emotional cues. The results revealed that horses significantly decreased the frequency with which they followed the experimenter's gaze and the total looking time during the gaze-emotional cue presentation in the Disgust condition compared to the Neutral condition. These results suggest the possibility that horses are sensitive to human emotional cues and behave on the basis of the meaning implied by negative human emotional cues.

Keywords: gaze following; horses; human–animal communication; sensitivity to emotion.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1

Figure 1

Setup for the study. (a) The experimental setting of the study: When the trial began, the experimenter (E) stood in front of the subject horse. When the subject horse (H) faced the experimenter, the experimenter quickly exhibited a gaze cue by turning her head to the back space of either the right or the left barrier. The dotted line shows the line of the experimenter’s visual line during the gaze-emotional cue presentations. (b) The photo of the experimental setting of the study: The assistant (A) guided the horse by lead to the experimental area. After the horse calmed down, the assistant looked at the floor. The assistant held the subject horse on a long- enough rope and allowed the horse to move freely within the range of the rope during the trial.

Figure 2

Figure 2

Emotional facial expressions.

Figure 3

Figure 3

Total frequency of gaze following. Total frequency of gaze following during two gaze-emotional cue presentations per trial of each experimental condition. The maximum value was 2 in each experimental condition because the experimenter presented gaze shift two times per trial. The median in each condition was 0 in the Happy condition, 1 in the Neutral condition, and 0 in the Disgust condition (* p < 0.05).

Figure 4

Figure 4

Total looking time of horses. Total looking time of the horses during two gaze-emotional cue presentations per trial of each experimental condition. The maximum total looking time was 180 frames because the experimenter presented each gaze-emotional cue for 90 frames (3 s). The median in each condition was 0 in the Happy condition, 19 in the Neutral condition, and 0 in the Disgust condition (* p < 0.05) (30 frames = 1 s).

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