We approached people, told them we were measuring their time for a project, and then told them how long they watched the exhibit. If they were still interested and not totally hostile, we asked if we could take their picture. Most people were either jaded or suspicious, and said no. One family said yes ("I'm not on the FBI wanted list right now, are you, dear?") but their picture came out really really dark. Maria, here, is the only person who had a visible picture and agreed to it. English wasn't her primary language (I think maybe she was Dutch?) and she seemed confused about what we were doing. Once she got the idea that we were doing a project of some kind, and timing people who watched the exhibit, she was perfectly happy to have her picture taken. Yay Maria!