Pretty damn good, really.
I helped my son feed a huge Morgan breed horse from his hand about an hour ago. (We were at the county fair)
I had to show him about twenty times that the huge beast would not hurt him. HE FINALLY DID IT! a few times. He allowed a Morgan to eat from his hand. This was one of the most enormous horses I have ever seen! (OH, and I have seen many a huge horse, in my time)
The fact that MY (autistic) son did this makes me feel pretty damn good, really.