SUMMARY: Trying to fix Boost's problem again.
Boost has never seemed to figure out rear crosses on tunnels. (That's where I send her into a tunnel and cross behind her, so that she needs to come out aware that I have changed sides.) She always turns towards the side I originally started on.
I've tried tackling this before, with a greatly shortened tunnel, running into the rear cross from different angles, tried starting from different distances from the tunnel to give more or less space for me to cross before she went completely in, tried being quiet, tried yelling her name, tried yelling "left" or "right" just so she could take the hint, tried doing exactly the same thing over and over to see whether she'd figure out that when I did XYZ, I always ended up on the opposite side... but no, I could do it 10 times (as an experiment) and every time she turned to the original side. So much for dogs figuring things out by repetition.
This weekend, what I finally hit on that seems to have some response is this: run straight down one side of the tunnel (parallel to the dog as she goes into the tunnel and runs through it), and she turns towards me. Repeat. Run straight down the other side of the tunnel, and she turns towards me. Repeat. NOW try a blatant rear cross, and she catches it. I've tried a few combinations of that sequence, and she seems to get the rear cross by comparison with running straight.
But if I go off and do a sequence of obstacles leading into a rear cross, boom, she's turning the wrong way coming out again.
Will have to research this a bit more. It's just very odd to me. Obviously some cue that I think that she should be getting that she isn't, or doesn't understand what it means, or that I give in different situations that means something different and I don't realize it. Maybe later this week I'll get out the video camera and try taping some sequences.