Mensa is an intelligent persons organization joined by Lisa. The other members of the Springfield group include Dr. Hibbert, Professor Frink, Comic Book Guy, Principal Skinner, and Lindsey Naegle. They gain control of Springfield, but after their experiment fails, they are shown up by Stephen Hawking, whom Homer refers to as Lisa's "robot buddy." Members must score at the 98th percentile or higher of a standardized, supervised intelligence test. Mensa is formally composed of national groups and the umbrella organization Mensa International.