Anna Tarasova ‘19

Dogs and horses have long been considered companion animals because of their long history of domestication with humans. Both are also heavily social animals, which means that they use emotional cues to learn about their environment and participate in their social group. The relationship between humans and horses stretches back 5,500 years. Within their species, horses have been seen to demonstrate physiological and behavioral responses to different facial expressions. Studies with dogs have shown that they can distinguish facial expressions in humans as well as potentially understand their meanings.

Dr. Kosuke Nakamura and his colleagues at the University of Tokyo and Hokkaido University have examined the cross-modal perception of human emotion by horses. Cross-modality refers to the use of multiple modes of sensory perception; this study included sight and hearing. Prior studies have shown that horses integrate these modalities in order to recognize familiar horses and humans. The method used in this study is known as expectancy violation: after being presented with a stimulus, the participant is presented with either an expected matching stimulus or an unexpected stimulus. Specifically, the first stimulus used on the horses was a picture of their caretaker or another person with a positive or negative facial expression. The horses then heard either gentle or scolding voices from another direction and turned in that direction. Expectancy violation was measured by the speed of their turning and the length of time spent looking at the speaker. The researchers found that the horses turned faster in the unexpected stimulus condition. They hypothesize that this is because they are able to recognize the positivity or the negativity of the facial expression and are surprised when the emotional quality of the vocal stimulus does not match that of the visual stimulus. These results support the notion that horses use a cross-modal approach when recognizing emotion.

References

1. K. Nakamura et. al., Cross-modal perception of human emotion in domestic horses (Equus
   caballus). Nature Scientific Reports (2018). doi: 10.1038/s41598-018-26892-6.  
2. Image retrieved from: https://commons.wikimedia.org/wiki/File:Biandintz_eta_zaldiak_-_modified2.jpg#/media/File:Biandintz_eta_zaldiak_-_modified2.jpg