Tunnel in the Sky possible inspiration?
Chapter 12 of the current best seller, "You Are Now Less Dumb," describes a 1954 psychology experiment that makes Lord of the Flies look like a documentary. A psychologist took two busloads of boys out to a park, and left them to their own devices. Over a span of several days, the scientists had to intervene repeatedly to stop the groups from killing each other, eventually terminating the experiment early because of this.
Although the citation for that chapter is a 1961 book by the chief psychologist, I am sure that it must've been reported much earlier. The timing leaves open the barest possibility that Heinlein heard of it in advance. When I read it, it instantly reminded me of Tunnel.
Here's a reference I googled from which you can get search terms to possibly find a contemporaneous publication:
http://www.age-of-the-sage.org/psycholo ... iment.html.