Gary,
I believe he mentioned in the email he sent me that the sliding anchor drill was not in his book.
All of Dr. Kidwell's drills are based on the assumption that target panic is a learned response, as you know from reading the book, but I will lay a little background for others. A learned response means that as you repeat a motion many times, your subconscious mind may begin to anticipate the response. For example, even though your conscious mind does not want to release the arrow until you come to full draw, your subconscious mind might trigger the release early. This is a difficult one to deal with directly. We can't just tell the subconscious mind not to release the arrow early, because the subconscious mind doesn't work that way. And yet we do want to turn the job of releasing the arrow over to the subconscious mind, because we introduce errors if we decide to consciously release the arrow. In order to re-train the subconscious mind, we need to somehow disconnect the stimulus/response trigger that is causing it to release the arrow early. This is the basis of all of Dr. Kidwell's drills. (My apologies to Dr. Kidwell if I botched the psychological explanation).
The purpose of the sliding anchor drill is to break the connection to the subconscious mind that tells it that we are getting close to the end of the draw, so it is time to release the arrow. The drill is to purposely draw past your anchor, maybe 1/2" one time, 1" another time, varying amounts, and then bring the arrow back to your anchor. Some times you won't draw past your anchor at all, but you'll never stop the draw at the same place as long as you're practicing the drill.
I know, I know, this is bad form, but it isn't as bad a form as short-drawing the bow. And it is possible to regain your back tension when you finally reach anchor before you shoot. I suppose the main thing you lose is that you use up some energy with this back-and-forth movement. Actually, I suspect some really good archers do this routinely. Many people have noticed Rick Welch occasionally draw past his anchor and then relax into it. Whether he does this on purpose or not, I don't know.
I needed a drill that I could use in tournaments, as that's the main time I have target panic. I don't usually have it when I'm shooting in my backyard or on the range for fun. Sometimes I get it when I'm shooting a very short-range target, like 15-20 feet away, even when I'm not in a tournament. So this morning I tried it at my range on the close targets, and found that I could come to full draw with no problems. Tomorrow, if it doesn't storm, I'll try it for the first time in a tournament.
Ironically, LongStick64's discussion of good form in his post above was indirectly the cause of some of my anxiety. I always felt that I had to shoot each shot in a tournament using good form, and yet something was preventing me from doing that. I think that if I know I'm going to purposely deviate from good form by drawing past my anchor, I will probably enjoy the tournament more and be able to reach my anchor more consistently. Granted, my score might not be as high as it would if I were able to shoot with good form anyway, but I can't do that until I solve this problem first.