A child with autism might:
• Not respond to their name by 12 months
• Not point at objects to show interest (point at an airplane flying over) by 14 months
• Not play “pretend” games (pretend to “feed” a doll) by 18 months
• Avoid eye contact and want to be alone
• Have trouble understanding other people’s feelings or talking about their own feelings
• Have delayed speech and language skills
• Repeat words or phrases over and over (echolalia)
• Give unrelated answers to questions
• Get upset by minor changes
• Have obsessive interests
• Flap their hands, rock their body, or spin in circles
• Have unusual reactions to the way things sound, smell, taste, look, or feel
Source: Centers for Disease Control and Prevention
http://www.cdc.gov/ncbddd/autism/facts.html