A type of pervasive developmental disorder defined by the Individuals with Disabilities Education Act (IDEA) as "a developmental disability significantly affecting verbal and nonverbal communication and social interaction, usually evident before age 3, that adversely affects a child's educational performance. Other characteristics associated with autism are engagement in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences." A diagnosis of autism is made when an individual displays 8 of 16 symptoms listed across three major areas: social interaction, communication, and restricted repertoire of activities and interests. (Fewer than 8 symptoms results in a diagnosis of PDD-NOS).