In 1963, research psychologist Robert Rosenthal wanted to know how our expectations affected our reality. In one of his earliest studies, Rosenthal brought in experimenters to his lab and had them take rats out of two separate cages – one labeled “smart” and the other labeled “dumb.” They were told that the smart rats had been bred for maze-racing, while the others had been tested as less capable. They had one week to prepare their rats for a maze race.
The “smart” rats outperformed the “dumb” rats by a landslide. It was then Rosenthal revealed the all the rats, regardless of what cage they came from, were the same, average kind of rat. They had been randomly labeled as smart and dumb.
So how come there was such a huge gap between the smart winners and the dumb losers? Simple – it was what was expected of them.