[quote name='Sarah5string' post='235081' date='Jul 8 2008, 04:45 PM']How exactly do you not think about what you're playing though?[/quote]
If you know something "off by heart" then it's stored in your subconscious somewhere. You can start off playing, and then not "think" about what you're playing. For example, lots of people play infront of the TV, and don't actually listen to what they're playing, but still play perfectly.
To what extent this is acheivable is something i'm not aware of, and I'd say I am naturally skeptical about things like this.
Another more common example, is where someone cannot remember a bass line that they know. However, when they start playing the song, it "comes back to them" and they play it perfectly. Whether or not they're actually thinking about what they're doing......... It's pretty pointless to play without listening to yourself IMHO.
It's just i've seen the phrase "finger memory" around quite a bit, and I don't like the way people misinterpret it (if it has a real meaning?). I'm no expert.