The research team that demonstrated yearlings perform much better if their training included feed rewards as positive reinforcement is now back to let us know that positive reinforcement gets ingrained in young horses’ minds for the long haul.

Several months after specific training with positive reinforcement, the same study horses were much more likely to remember what they had learned in the initial study compared to a control group, according to the group led by Carol Sankey, MSc, a PhD candidate in ethology (the study of animal behavior) at the University of Rennes in western France, who presented her findings during the 2009 Equine Research Day in Paris. These horses were also generally friendlier with humans, including humans they had never seen.

"Using positive reinforcement to train young horses has the double advantage of creating effective, long-lasting results and of strengthening the horse-human relationship."
–Carol Sankey

The initial experiment, also led by Sankey, tested 23 yearlings divided into two groups: positive reinforcement and no reinforcement (control). The horses were taught to stand still following a vocal command ("Stay") while an experimenter (Sankey) performed various handling tasks with them (grooming, putting on a surcingle, checking temperature, etc.). The positive reinforcement group consistently learned faster and showed more docile behavior towards the experimenter. (Read more: "Study Correlates Food Rewards with Positive Responses during Training")

Six months later, the horses in the positive reinforcement stood still nearly 50% longer during the handling tasks than the control group, Sankey said. To test their comfort level with humans, she stood quietly in an open paddock with the horses. Sixty percent of the positively reinforced horses spontaneously chose to remain within a half a yard of her, whereas only 15% of the control horses came this close.

When a different experimenter, unknown to the horses, carried out the same tests another two months later, the positively reinforced horses stood still an average of 26% longer than the control horses. In the open paddock, 40% of the these horses stayed close to her, as opposed to only 7% of the control horses.

"Using positive reinforcement to train young horses has the double advantage of creating effective, long-lasting results and of strengthening the horse-human relationship," Sankey said. "Through this technique, horses develop a positive image of humans, and we now know that they generalize this image to other people."

Nonetheless, the horses clearly favored their initial trainer to a new experimenter, spending more time close to her and showing more signs of affiliation, such as sniffing her, Sankey reported. "Like in a herd, the horses displayed tendencies of bonding more to one person than another," she said.

During the months between experiments, the horses received no training of any kind. Their only interactions with humans occurred when they received feed and hay in their bins. No reinforcement was given to either group during the new tests.

Full details of the study, "Positive interactions lead to lasting positive memories in horses," are scheduled to be released in a forthcoming issue of Animal Behaviour.