Date: 25 JUL 1980 0845-EDT
From: ZIM at MIT-MC (Mark Zimmermann)

How long does it typically take for one to be able to work with only
a mental image of the cube? (As in"blindfold" chess, soma, pentominoes.
I do not know of anyone who can do it blindfolded (I cannot). However,
a few days ago mine fell into a swimming pool and I did it underwater with
five gulps of air.