This is a question I have been considering since the owner of the horse - a seven year old grullo quarter horse - I was leasing had to move him to a different facility. They moved him unexpectedly in April and I have not been able to see him. It has been almost three months since he left and since I cooed at him and scratched his ears. Now, with the possibility of seeing him again, I wonder if he'll remember me.
An article titled "Horses Never Forget Human Friends" by Jennifer Viegas makes me feel hopeful that my special equine buddy will be as excited to see me as I am him. The article summarizes a study that was conducted at the University of Rennes in Chamberet, France, involving positive and negative reinforcement among twenty Anglo-Arabian and three French Saddlebread horses. Generally, the researchers determined that horses remain loyal to humans with whom they have had positive encounters with in the past. They also remember people even after a long period of separation.
You can find Jennifer Viegas's article at: http://news.discovery.com/animals/horse-friends-memory-trainers.html
