"I would say rather that the obvious differences disappear when you are
required to conceptualize them and on the basis of that conceptualization
make a large number of discriminations in a limited amount of time."

One is asked, is this amp the geewiz mk 77 or the fuddy duddy box store
brand? The person being tested having said previously that the mk 77 has
such a distinct "audible signature" that he would know it anywhere. One
isn't ask to characterize the difference, just to note which is the mk 77
or simply to say something is different, any difference for any reason,
between amp a or b. The under great pressure is a strawman, people aren't
required to do x number of identification in y time.