I remember reading something kinda sorta similar in college - they set up an experiment where the subjects thought they were taking some kind of aptitude test. While they were taking the test, they started pumping smoke into the room from the “loudspeaker” I think it was. When it was a room full of people, no one wanted to be the first one to stand up and possibly look foolish. The room would get quite smoke filled before someone would finally get up and seek attention. When people were alone in the room, they got up right away.
Another one was a study on personal involvement. They would have a couple set up their stuff on a blanket at the beach near other people and then walk off without saying anything to anyone. A few minutes later, someone would come by and take off with their tote bag. No one hardly raised an eyebrow. Conversely, if they asked the people closest to their towel to “keep an eye on our stuff while we run to the restroom” they would immediately get involved and take off after the guy yelling at him.