Autism is a disorder first diagnosed in childhood and is included in the category of pervasive developmental disorders. Autism is categorized by deficits or abnormal behavior in three areas: social interaction, communication, and range of interests. Autistic children show avoidance of eye contact and of social interaction in general. They do not develop normal peer relationships and they do not show typical desire to share toys or engage in social play. Their communication skills are also abnormal, with delayed language development, improper use of personal pronouns and stereotyped, or repetitive use of language (“Your parents is coming! Your parents is coming!”). Finally, they show a restricted range of interests, with intense and obsessive focus on particular objects or topics. For example, a person with autism can develop an obsessive interest in trains and memorize the entire schedule of a given transit system. Additionally, there is a rigid adherence to routine and marked distress when the routine is violated. Some of these symptoms relate to another characteristic, one that is well researched but not yet captured in the DSM system.

People with autism frequently suffer from a deficit in theory of mind. This refers to the ability to understand another person’s subjective experience and is a necessary first step in empathy. Because of their impaired theory of mind, people with autism can have a very difficult time making sense of social interaction and often find social situations extremely stressful.