Nah, I'm the blind one - I got 12.
I think in order to get a really reliable result you have to repeat that over and over again in order to eliminate random effects. Also we would all have to do it under standardised conditions, with carefully adjusted monitors, identical lighting etc. Still it's fun to do it just like that - even though it was about to drive me crazy occasionally.
Also, they should offer a special version of the test - only for metalheads - where you have to distinguish different shades of black.
Cheers!
Markus