Alix Spiegel: There's a man named Bob Rosenthal. He's a research psychologist. And early in his career, he did this thing. He went into his lab late at night and hung signs on all of the rat cages. And some of the signs said that the rat in the cage was incredibly smart. And some of the signs said that the rat in the cage was incredibly dumb, even though neither of those things was true.
Bob Rosenthal: They were very average rats that you would buy from a research institute that sells rats for a living.
Alix Spiegel: So then Bob brings this group of experimenters into his lab, and he says, for the next week, some of you are going to get these incredibly smart rats. And some of you are going to get these incredibly stupid rats. And your job is to run your rat through a maze and record how well it does.