I've noticed a few things about handling sight reading mistakes since I started working on it last year. The same advice always comes up when I read about it: Don't let any mistakes go to your head or otherwise affect the rest of your playing. Take note of them so you can revisit the trouble spots after you finish the piece, but don't ever let the beat drop. (The Beastie Boys are known for that. Don't follow their example.)
I realized that this advice ought to apply not only to mistakes in the past, but also in the present and near future. I feel like the most important aspect of sight reading is reading ahead. Nearly all of my screw ups can be attributed to not maintaining a minimum distance ahead of the current note. Anything that pulls my focus away from reading ahead increases the chances of a mistake. So if I just dropped a clunker, or I'm in the middle of doing so, or I'm about to because I just misread a note, I need to put it out of my mind immediately and keep reading.
It's very much like a portable CD player with "5-second shock resistance." The player reads the CD 5 seconds ahead of what's playing in your ears. If you shake it, it can't keep reading, and that 5-second buffer diminishes. It'll catch up to the full buffer without skipping if you let it be. But if you shake it for more than 5 seconds, it can't maintain any buffer, and your music skips. (I suppose a more modern example would have been online videos. Keep that buffer line ahead of playback.)
With that strategy, my confidence increased dramatically. I still get tripped up if I lose my reading buffer. It's tough to pick it up and build a lead again, because I need to read faster than normal, but I'm slowly getting better at it.
I've been wondering lately about the best approach for dealing with missed notes. The way I see it, I have 3 options when I think I'm about to screw up. I can reread the note and try to get it right, I can make my best guess based on the contour of the melody and/or my instincts, or I can play nothing, as if the note were a rest. From my experience, and I'm no professional at this, trying to get the note right is a bad idea. It takes my attention away from reading ahead, and I often end up shifting to a new note as I'm playing it, making it apparent to any listener that I made 'im a steak.
Now I'm torn between guessing just to play something where I know there should be a note versus leaving it silent. I can imagine appropriate situations for both. In an audition for my college jazz band a few years ago, the instructor, Bobby Bradford, told me to keep playing and don't worry if it's wrong. If I know there's supposed to be a note or chord coming up, but I can't figure it out in time, I should still play something to demonstrate that I'm half with it (and in case I accidentally play the right thing). On the other hand, if I were rehearsing a piece with a band for the first time, playing wrong notes might throw the other musicians off, while skipping missed notes entirely probably wouldn't. Come to think of it, I can't think of a practical application for guessing the note outside of demonstrating abilities in an audition.
So what do you think? Guess or silence? Other situations in which one or the other is appropriate?