Dr. Schulman

Dr. Schulman is an imaginary psychologist. He appeared when Lisa asked how many times they could watch Homer being chased by an angry mob before they get psychologically affected, But when Lisa started talking to him, Marge woundered why was Lisa talking to an empty seat. It's also implied that Lisa "sees" him every thuesday, as she says "See you next Tuesday, Dr. Schulman. Oh, right. You're in Maui."