I think that it all comes down to what Dr. Maxwell Maltz said in his great book "Psychocybernetics:"
" Experimental and clinical psychologists have proved beyond a shadow of a doubt that the human nervous system cannot tell the difference between an 'actual' experience and an experience imagined vividly and in detail."
its safe to say that I train some martial arts. Im not that good really, but most people really suck, so I feel ok about that - Sunfist
Sometime blog on training esp in Japan
But by now it is a proven scientific fact.