Sign language and motor functioning in students with autistic disorder.

Sign language production of 14 low-functioning students diagnosed with autistic disorder was examined. Videotapes of the students signing with their teachers were analyzed for frequency and accuracy of sign location, handshape, and movement production. The location aspect of signs was produced more accurately by the subjects than either the handshape or movement aspects. Wide individual differences were evident among the students in the number of signs they produced, accuracy of sign formation, and performance on measures of motor functioning. Students' sign vocabulary size and accuracy of sign formation were highly correlated with their performance on two measures of apraxia and with their fine motor age scores.