The single most important paper for programming language designers to read came out in 2000. It wasn’t written by a computer scientist, mathematician, or physical scientist. It was written by a couple of professors studying psychology and marketing: “When Choice is Demotivating: Can One Desire too Much of a Good Thing?” Iyengar, S. S., & Lepper, M. Journal of Personality and Social Psychology, 79, 995-1006. (2000).