The most obvious sign that a child has autism is their inability to interact socially. Babies and infants won't respond to smiles, vocal games, or other stimuli and activities around them. Children won't follow other people with their eyes, or make eye contact. Facial expression and body language are neither understood nor expressed by children with autism. They may also not be able to develop emotional and social relationships.
Many children with autism find it difficult to develop language skills, and they are unlikely to start up a conversation. However, it's not unusual for a person with autism to echo phrases they hear in conversation or have heard in the past.
This tendency to repeat is apparent in other behaviours associated with autism. Certain movements or motions, such as flapping the hands or twisting the body, will be repeated over and over again. Children don't participate in imaginative play but can learn and imitate actions. For instance, a child who appears to be playing telephone - dialing, talking, hanging up - will act this out in exactly the same way and order the next time. This doesn't indicate an active imagination but rather repetition of a learned behaviour. Learning also occurs in an erratic manner - what a child appears to have learned one day may be forgotten the next.
Children with autism frequently prefer to keep a strict order around themselves. Play might consist of lining up objects, or even of being fascinated by some aspect of a toy (its texture, smell, or colour) rather than its function. People with autism often prefer routines to be strictly maintained - serving a meal 5 minutes late can cause a tantrum. An object moved out of its usual place can be extremely distressing, causing a reaction that will only stop when the object is moved back to its usual place.
Other behaviours of people with autism include:
- acts of self-injury
- abnormal eating, drinking, or sleeping habits
- lack of fear, or irrational fears
- limited activities and interests
- mood abnormalities
- short attention span
- unusual responses to stimuli (lack of interest or oversensitivity)
Although people with autism can be developmentally impaired in many ways, they might also have particular strengths which differ from one person to the next. These may include a talent for music or mathematical calculations, as well as other strengths.
Autistic children often have gastrointestinal disorders (abdominal pain, constipation or diarrhea, gastroesophageal reflux) as well as other health issues, including sleep disorders (not wanting to got to bed, insomnia, altered sleep-wake cycles) and epilepsy. It is not uncommon for autistic children to self-injure.