On a trail yesterday, I took a wrong turn and ended up going into a very overgrown area, large enough for my horse to get through with no problem, but not with ME astride. At first it was hard to see this as the path was curving. As I trotted into it, the horse came to a complete dead stop, and would not go further. My riding partner was aghast at this. It seemed like the horse knew I would get thrown off by the overgrown branches in the way. This seems like reasoning power to me!