You really are on the same wavelength with your friends

Researchers from UCLA and Dartmouth College are able to have a computer program determine with 48% accuracy friendships between two people based on neural similarities.  Accuracies of identifying a friend of a friend were at 39%, friend of a friend of a friend at 31%, and friendships further removed than that at 47%.  When the program was wrong, it was usually only off by one category.