language disorders can occur during a child's development or they can be acquired. This acquisition usually follows a normal neurological development and is brought about by a number of causes such as head trauma or irradiation. Features of an expressive language disorder vary, but have certain features in common such as: limited vocabulary, inability to produce complex grammar, and more lexical errors. If it is a developmental disorder, the child will have difficulty acquiring new words and grammatical structures. The child will often begin speaking later than his/her peers and progress at a slower rate linguistically. Due to the very nature of these disorders, the child may struggle with academics and socializing with peers. Experts that commonly treat such disorders include speech pathologists and audiologists. Psychopathology of language A special class of language disorders is studied by the psychopathology of language. Its topics of interest range from simple speech error to dream speech and schizophasia. Childhood language disorders During childhood the most common type of disruption in communication is a language disorder. In most cases, language development is predicable and referrals for evaluation may be needed in cases where a child's language development is atypical. Language disorders among children are present when a child is experiencing substantial difficulty regarding their language development. Among young children, language disorders have been associated with higher rates of social difficulties and anxiety. Specific language impairment Specific language impairment (SLI) is a developmental language disorder among children that has no known cause and cannot be attributed to any physical or intellectual disability, environmental factors such as deprivation, hearing loss, or any other underlying etiology. SLI is characterized by abnormal development of language that includes a delay in the onset of language, simplification of grammatical structures and difficulty with grammatical morphology, limited vocabulary, and problems understanding complex language. Children with SLI tend to begin speaking at a later age and have a smaller vocabulary than their peers. Among the language disorders that are present during childhood, SLI is one of the most prevalent, affecting roughly 7% of children. While children with specific language impairment have difficulty with language production, they are noted to have normal levels of intelligence. Autism spectrum disorder Autism spectrum disorder (ASD) is a term used to define a group of developmental disorders that are characterized by disruption in communication and social abilities, limited eye contact, exhibiting repetitive behaviors, and having limited interests.