Maybe it doesn't make you work faster, maybe it just make you hungry?

Do you know that story? A scientist has a trained flea, he tells it to jumps, and it does. Then he takes a tweezer and rips the flea's legs. He tells it to jump again, and of course it doesn't. So he takes his favorite pen and writes in his research book "when you rip a flea's legs, it becomes deaf"