Individuals with ASD exhibit significant deficits in one or more of the following language domains:
• PHONOLOGY: the phonemes of a language, as well as the rules for combining and using phonemes. Although many children with ASD have been diagnosed with a phonological disorder, the majority do not have significant deficits in the phonological system.
• SYNTAX: the possible ways in which words are combined to form sentences in a language. Individuals with ASD have considerable difficulty applying syntactic rules in their language, and a generalized delay is observed in this area.
• MORPHOLOGY: the rules governing how morphemes are used in a language. Research has shown that individuals with ASD produced fewer past tenses, fewer partial knowledge questions (questions that cannot be answered with "yes" or "no"), and made errors in the use of pronouns (e.g., "You want to eat" when referring to themselves and should say "I want to eat").
• SEMANTICS: the meaning of words and word combinations in a language. This is an area with considerable deficits for most individuals with ASD. Two types of difficulties are observed: in organizing information and in using this information for thinking and problem-solving.
• PRAGMATICS: the rules related to the use of language in conversation (social language). Numerous studies have shown that all individuals with ASD experience difficulties in pragmatics, as this is the language domain in which they display the most and the most significant deficits.
