We Can Only See 30 Shades of Gray Meanwhile, 'Fifty Shades' shown to 'SpongeBob' audience By Rob Quinn, Newser Staff Posted Feb 20, 2015 2:39 AM CST Updated Feb 20, 2015 3:21 AM CST 12 comments Comments How many shades can you see? (Wikipedia/Jacobolus) (Newser) – Human beings can only see around 30 shades of gray, according to a bit of trivia Popular Science says it found in a research paper and has decided to share "for no particular reason whatsoever." The exact number of shades of gray we can distinguish will vary a little depending on things like lighting conditions, the magazine says. Meanwhile, in Fifty Shades of Grey news, a theater in Loveland, Colo., accidentally showed the beginning of the erotic thriller to an audience expecting the SpongeBob SquarePants movie earlier this week. "People ran out of there," a moviegoer tells the Denver Post. "You could hear little kids going, 'SpongeBob! SpongeBob!' as the parents were dragging them out."