The three training zones of dressage, from the horse's perspective: 1) No problem; totally got it. 2) Um, I'm not completely sure what you want, and it's making me nervous. 3) Ack! You're freaking me out!
During my last few rides, I've been spending a lot less time in zone 1 and a lot more in zone 2. For one thing, I'm making a conscious effort to use the whip a lot more (a light touch only -- Willow would go into orbit with anything more). Willow has always tended to respond to the whip not by going forward but by sucking back and threatening to buck. That response has conditioned me not to use the whip when I should. So lately I've been using the whip in leg yield at the walk to reinforce the sideways leg aid. That has seemed to loosen her up and let her accept light touches without resentment. It's starting to carry over into trot. In canter, I still expect mighty leaps whenever I use the whip. Hello, rafters.
In warmup I've also been doing a lot of simply shoving Willow's body sideways without worrying about what her head is doing. I go from leg yield to shoulder in to half pass back to leg yield. At first this definitely edged her towards zone 3, but now we're back in zone 2 territory. She can do all these things in zone 1 if I let her lean, but I'm making her do them without leaning, and that is puzzling to her. And when she is puzzled, she points her nose skyward. But after awhile she realizes I'm not going to fight her or pull on her, and drops back onto the bit on her own.
Tonight I loved where we ended up: big trot, on the bit without leaning, collection to medium to collection. And all this in the snaffle! Progress.