Do an experiment today: write down the posters, pictures, statues or other decorative elements in a place where you go frequently. For instance the corridor leading to your office, the square you run through to get to the bus station, the pub where you like to have a beer, the bank - what ever place where it's natural that there are decorative elements. Then go there and check. How much did you remember? Would you have noticed if one was removed? Would you be able to tell if it was?
Today we were four professors staring at a blank space at the wall. A picture is gone. When did it go away? None of us could tell.