Children with autism understand fewer words than their verbal ability would suggest, according to a study published in December in the International Journal of Language and Communication Disorders.
Children generally understand words before they are able to pronounce them. For example, a child who uses about 20 words typically understands about 160.
In the new study, researchers evaluated the vocabulary of 152 preschoolers with autism — ages 29 to 54 months — who have a well-described delay in language. They found that one-third of the children are more impaired in their ability to understand words than in their ability to speak them.
Overall, these children still understood more words than they spoke, but the difference between the two numbers is smaller than the recognized norm.
The researchers used several tests to measure verbal ability. Parents first scored their children on the Vineland Adaptive Behavior Scales and the Autism Diagnostic Interview-Revised. Researchers then assessed the children using the Autism Diagnostic Observation Schedule, the Preschool Language Scales and components of the Mullen Scales of Early Learning.