I remember hearing about a social scientist "discovering" that in any classroom he visited, there always seemed to be 4 kids that were either all friends, or we

I remember hearing about a social scientist "discovering" that in any classroom he visited, there always seemed to be 4 kids that were either all friends, or were all not friends. He wrote a paper that attempted to explain this using social theory/group dynamics... (This was told by my Discrete math professor when learning about Ramsey's Theorem )