TABLE 1.

Characteristics of Specific Language Impairment (SLI)

Diagnostic criteria

• Language is significantly below level expected from age and IQ, usually interpreted as scoring in the lowest 10% on a standardized test of expressive and/or receptive language

• Nonverbal IQ and nonlinguistic aspects of development (self-help skills, social skills) fall within broadly normal limits

• Language difficulties cannot be accounted for by hearing loss, physical abnormality of the speech apparatus, or environmental deprivation

• Language difficulties are not caused by brain damage

Common presenting features*

• Delay in starting to talk; first words may not appear until 2 years of age or later

• Immature or deviant production of speech sounds, especially in preschool children

• Use of simplified grammatical structures, such as omission of past tense endings or the auxiliary “is,” well beyond the age when this is usually mastered

• Restricted vocabulary, in both production and comprehension

• Weak verbal short-term memory, as evidenced in tasks requiring repetition of words or sentences

• Difficulties in understanding complex language, especially when the speaker talks rapidly

^*SLI shows substantial heterogeneity, as well as age-related change, and diagnosis does not depend on presence or absence of specific language characteristics.