Be it in horses or humans, stress can affect learning ability. Some of us actually appear to learn better with a little bit of stress. But in a new study, French researchers have shown that, at least in horses, stress seems to consistently impair learning. And the degree of that impairment depends on training method and the individual horse.

“Our study is the first to demonstrate that stress affects equine learning differentially according to the type of reinforcement in interaction with personality,” said Mathilde Valenchon, PhD, of the University of Strasbourg, of her research conducted at the French National Institute for Agricultural Research Val de Loire. Valenchon presented her work during the 2016 International Society for Equitation Science conference, held June 23-25 in Saumur, France.

Specifically, stress impaired learning more when the horses learned a task through positive reinforcement as opposed to negative reinforcement, Valenchon said. In positive reinforcement, handlers reward horses’ behavior by giving them something they enjoy, such as a treat. In negative reinforcement, handlers reward behavior by removing something unpleasant, such as pressure.

Furthermore, horses with fearful personality traits tended to be more impaired by stress when learning a task, regardless of the kind of reinforcement, she added