Theory of mind

Theory of mind is the ability to understand that other people have their own minds with their personal state of knowledge, their personal beliefs, wishes and intentions, and that these may differ from one's own mind. Autistic people typically show an impaired ability to recognize other people's minds. Therefore, they experience difficulties with explaining and predicting other people’s behaviour. This leads to problems in social communication and interaction. Children on the autistic spectrum usually develop the theory of mind more slowly than other children. They have difficulties with it throughout their lives. However, autistic people's performance on theory of mind tasks varies.
For testing whether someone lacks the theory of mind, the "Sally-Anne" test is performed. The child sees the following story: Sally and Anne are playing. Sally puts her ball into a basket and leaves the room. While Sally is gone, Anne moves the ball from the basket to the box. Now Sally returns. The question is: where will Sally look for her ball? The test is passed, if the child correctly assumes that Sally will look in the basket. The test is failed if the child thinks that Sally will look in the box. Children below the age of four as well as older autistic children typically fail this test.