Forexample,theathlete may hear a tone, the presence of which indicates the Occurrence of EEG alpha ac- tivity of 20 pV or greater. He may recognize that whenever this tone appears, he coincidentally experiences a relaxed, “idling” mental state where he is not thinking a b o u t a n y t h i n g i n p a r t i c u l a r . By s u s t a i n i n g t h i