I found even more articles. I'll create another post for you soon. One of them reminded me of an experience I had while horse-shopping.
I was looking at a Chestnut Arab mare, about 15 hands, and was trying to do some groundwork with her. Playing some of the basic Parelli games, you know. I don't really remember how she did, but it must've been somewhat alright, because I proceeded to do the Circling Game. I couldn't get her to move! In honesty, I probably could have, but I didn't want to really Phase 4 her, since 1) her owner was watching, and 2) I wasn't sure why she was doing it, fear or disrespect or confusion. So, I asked a friend watching if she wanted to play with the horse. She said sure, and hopped in.
Well, she tried the Circling Game with her, and she couldn't get the horse to STOP moving. It was incredible. From the time I had walked out of the pen to the time she had walked in was like 20 seconds, maybe. But yet, the horse had completely changed. "How interesting!" My friend is an extrovert, and I'm an introvert. What a sensitive horse!
