Some children show signs of autism spectrum disorder in early infancy, such as reduced eye contact, lack of response to their name or indifference to caregivers. Other children may develop normally for the first few months or years of life, but then suddenly become withdrawn or aggressive or lose language skills they've already acquired. Signs usually are seen by age 2 years. Each child with autism spectrum disorder is likely to have a unique pattern of behavior and level of severity — from low functioning to high functioning. Some children with autism spectrum disorder have difficulty learning, and some have signs of lower than normal intelligence. Other children with the disorder have normal to high intelligence — they learn quickly, yet have trouble communicating and applying what they know in everyday life and adjusting to social situations. Because of the unique mixture of symptoms in each child, severity can sometimes be difficult to determine. It's generally based on the level of impairments and how they impact the ability to function. Below are some common signs shown by people who have autism spectrum disorder. Social communication and interaction A child or adult with autism spectrum disorder may have problems with social interaction and communication skills, including any of these signs: 
Fails to respond to his or her name or appears not to hear you at times
Resists cuddling and holding, and seems to prefer playing alone, retreating into his or her own world
Has poor eye contact and lacks facial expression
Doesn't speak or has delayed speech, or loses previous ability to say words or sentences
Can't start a conversation or keep one going, or only starts one to make requests or label items
Speaks with an abnormal tone or rhythm and may use a singsong voice or robot-like speech
Repeats words or phrases verbatim, but doesn't understand how to use them
Doesn't appear to understand simple questions or directions
Doesn't express emotions or feelings and appears unaware of others' feelings
Doesn't point at or bring objects to share interest
Inappropriately approaches a social interaction by being passive, aggressive or disruptive
Has difficulty recognizing nonverbal cues, such as interpreting other people's facial expressions, body postures or tone of voice
 Patterns of behavior A child or adult with autism spectrum disorder may have limited, repetitive patterns of behavior, interests or activities, including any of these signs: 
Performs repetitive movements, such as rocking, spinning or hand flapping
Performs activities that could cause self-harm, such as biting or head-banging
Develops specific routines or rituals and becomes disturbed at the slightest change
Has problems with coordination or has odd movement patterns, such as clumsiness or walking on toes, and has odd, stiff or exaggerated body language
Is fascinated by details of an object, such as the spinning wheels of a toy car, but doesn't understand the overall purpose or function of the object
Is unusually sensitive to light, sound or touch, yet may be indifferent to pain or temperature
Doesn't engage in imitative or make-believe play
Fixates on an object or activity with abnormal intensity or focus
Has specific food preferences, such as eating only a few foods, or refusing foods with a certain texture
 As they mature, some children with autism spectrum disorder become more engaged with others and show fewer disturbances in behavior. Some, usually those with the least severe problems, eventually may lead normal or near-normal lives. Others, however, continue to have difficulty with language or social skills, and the teen years can bring worse behavioral and emotional problems.