We had a day and a half where no one showed up, so I had to do more groundwork. I taught him some shoulder in. As predicted, I can ask from his left side and get a pretty good shoulder in on three tracks. Ask on his right however and he wants to walk away from the wall (and cut me off) instead of bending and crossing legs. I got a bit frustrated for a number of reasons but then realized something. Yes he is bad on that side, but also we haven't worked on it in a while. So not only do we have to work a lot more on that side, I needed to go and perhaps review some more basic movements! Remember this game Aslan? That's better! His shoulder-in slightly improved on that side, but it really highlighted that I need to double my efforts on his right and not get frustrated if he does poorly on his right; review the basics more often on this side too.
Which brings to mind, a common fault in riders/trainers (including me!). When we work on a behavior and suddenly they get bad at it, the first reaction is: I taught you this !!! Why are you ignoring my cue??? Which is exactly what I thought on his shoulder-in movements. Of course like an idiot, I pressed harder. In the area of negative reinforcement, this makes sense, because the horse probably isn't all that motivated to perform in the first place, so you have to let them know that you will increase the pressure if they ignore it or try to evade. But in positive reinforcement, generally the horse enjoys performing and doesn't look for ways to get out of work unless the trainer is screwing up. Yes I screwed up. I eventually clued in, stopped, went back and gave him a refresher in "leg yield". Sure enough he was not performing well at the leg yield from pressure on his right hand side; so forget about asking for a shoulder in. But my attitude could have really killed this exercise for him had I not stopped and corrected myself as well.
It is so easy to go into the frame of mind that the horse is deliberately ignoring or resisting cues, especially if you are used to traditional horsemanship. In my case, I was slipping back to the old frame of thought. I thought we had practiced leg yield and side pass enough. But when I think about it, Aslan has to make this decision, not me. If we do it 300 times and he still sucks, then he still needs more practice. Duh. I remember a Grand Prix dressage rider (Natasha Althoff) saying that you can only be an expert at something once you've done it 10,000 times. That's a lot. Aslan has maybe done side pass to the left, er 100 times? If that? My bad.