Is your horse an optimist or a pessimist? Researchers from Germany have discovered a surprisingly simple way to find the answer.

A joint study conducted by teams at University of Regensburg, University of Hohenheim and Nuertingen-Geislingen University investigated the potential correlation between a horse’s state of mind and his motor laterality—that is, his preference for using the limbs on one side of his body or the other.

The link between motor laterality and emotion is well established in humans and rodents, explains Konstanze Krueger, PhD, who worked with Isabell Marr, MSc, and her team on the study. “It has been shown that rodents and humans who undergo stress, especially while maturing, tend to shift their motor laterality to the left—and are ultimately more likely to be left-handed. These animals tend to be more pessimistic.”

This leftward shift, Krueger continues, “is caused by an enhanced use of the right brain hemisphere, which, in addition to controlling motor function on the left side of the body, is in charge of fight-or-flight reactions and is most active in emotional situations. In horses, it has been proven that animals differ in their laterality depending on the emotionality of test situations. When horses were stressed, or challenged with frightening objects such as umbrellas, they displayed increased left laterality.”

For the study, 17 horses were first trained to approach a box placed in either a “positive” location, where the horses would be able to open it with their muzzles and reach a carrot inside, or a “negative” location, where the box was impossible to open. Once it was clear the horses understood the difference between the locations, the researchers determined the horse’s cognitive bias (emotional state) by placing the box in a new, ambiguous location. They then noted which limb the horses stepped forward with in heading toward the box.

Horses who approached the ambiguous box faster and spent more time trying to open it—indicating an “optimistic” outlook, according to the researchers—were more likely to start walking toward it with a right limb. Horses who started walking with a left limb approached the box more slowly and gave up on opening it more quickly, indicating a more “pessimistic” view of the situation. The researchers found no correlation between other forms of motor laterality—such as which limb was in a more forward position when the horse was resting—and emotion.

A horse’s mental state has implications for those who care for and work with him, says Krueger. “A negative (pessimistic) horse may be more cautious than a positive (optimistic) horse. He may expect new situations to be unpleasant, while positive horses would have no expectations, or positive expectations for a novel situation. For example, in training for a new task, a negative horse may be more reluctant to participate while a positive horse would fully follow the trainer and try to accomplish the task right away.”

Krueger says that management and training can influence a horse’s attitude, but his fundamental outlook may be hard to change.

“These [pessimistic] animals may calm down when they are kept in a positive, pleasant environment, but will tend to make negative decisions—or tend to quit cooperating—in any new, challenging or stressfulsituation. Usually a skilled trainer is able to manage this temperament and can avoid putting the horse in questionable, unpredictable or unpleasant situations. Positive, optimistic horses are far more easy to train and to handle.”

Reference: “Evidence for right-sided horses being more optimistic than left-sided horses,” Animals, November 2018

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