When horses are grooming each other, they usually focus in one particular site right on top of the withers there or a little bit in front. That's the area where we know that the heart rate will lower during this grooming session. It lowers by about 10 beats per minute.
So it's a very good thing to think about as a site for reward. that you can use your fingers and scratch the horse there fairly vigorously as a primary reinforcer. In other words, to reward certain behaviours. And if you say the word good boy when you're about to scratch them there, then the word good boy, as long as you pair it 100% consistently, the word good boy will have the same kind of effect. So we're tapping into something that's really ancient and hardwired into the horse with that particular reward system.