Interesting article, this.
But his background is in cognitive psychology; he seeks to identify the basic mental processes that are common to all cases of autism and that link autistic behavior to its biological roots. In 1985, while still a graduate student at University College London, he made a breakthrough discovery of one such process. With his advisers Uta Frith and Alan Leslie, he presented autistic children with dolls named Sally and Anne, and the following story: Sally puts a marble in her basket and leaves the room. Anne takes the marble and hides it in her own box. Sally comes back and looks for her marble – where does she look?
A normal 4-year-old child says that Sally will look for the marble where she left it, in her basket. The child may even giggle at the joke on Sally. A kid with Down’s syndrome will get it right too. But autistic children don’t get it right. They say Sally will look in Anne’s box – because after all, that’s where the marble really is. They have no notion, Baron-Cohen discovered, of where Sally might think the marble is. They lack a “theory of mind” – abstract jargon for the simple realization, which the normal child comes to at around age 4, that other people have thoughts and intentions that may differ from his own. And that figuring those thoughts out helps him to understand what those people say and do.