I cannot for the life of me remember the context, but I remember reading about skills that can't be taught; only learned; chicken-sexing was one of these.
I think it's kind of like teaching someone how to ride a bike. No amount of theory and coaching will help until the connections form in their brain.
Smarter everyday has an interesting video[1] on this phenomenon where he showed that it takes considerable effort to learn to ride a "backward" bike and once you do, you will forget how to ride a normal one and need to relearn it.
Note that he didn't entirely forget how to ride a normal bike, It only took him a couple tries for his brain to switch the normal-bike-riding-program back on.
Yeah, I recall reading about one that had something to do with watchmen in London/Britain during WWII being able to spot German fighters in the air...? The best way they found to train them was to simply have them watch experienced ones do it for some period of time.
