Autism involves impaired social interaction, impaired communication and lack of developmentally appropriate behavior, interests or activities.
Deficit in social skills eg abnormal eye contact, failure to orient name, failure to use gestures to point or show, lack of interactive play, failure to smile, lack of sharing & interest in other children, and often withdrawn and spends hours in solitary play with restrictive or repetitive interests and behaviors.
Impaired social interaction showed as impairment in joint attention, deficits in empathy for what another person might be feeling and deficits in understanding what another person might be thinking.
Autistic child also presents with deficit in language and communication (eg nonverbal or having some speech), aberrant play skills (eg little symbolic play, preoccupation with parts of objects), variation in intellectual functioning, heightened awareness to stimuli and lowered sensitivity to stimuli.