Echolalia and the use of memorized scripts are compensatory mechanisms in children who rely on an excellent verbal memory to circumvent difficulty in word retrieval, responding to open-ended questions, and the organization of coherent discourse. What is universally impaired in autism and distinguishes autism from specific developmental language disorders is very impaired pragmatics, that is, the conversational use of language. Except for mildly affected children with so-called Asperger syndrome, children with autism acquire language late. Those who remain nonverbal tend to have persistent severe comprehension deficits and to be mentally deficient. Other Symptoms Children with autism may have motor deficits such as hypotonia, clumsiness, toe walking, and repetitive stereotyped movements and activities, as well as sensory symptoms such as atypical perception of somatosensory, visual, auditory, gustatory, and olfactory signals.
Some children engage in distressing self-injurious behaviors.
Perseveration, rigidity, and obsessions may be prominent. Many have prominent sleep disorders. Disorders of attention may consist of too long an attention span for favorite activities and unusual tolerance of monotony, often paradoxically associated with a very short attention span for other activities. Some children are frankly hyperactive and disorganized and may be mistaken from children with primary attention deficit disorders with hyperactivity. A universal deficit is difficulty or inability to pay joint attention to an activity introduced by another person.