Acquisition of modified American sign language by a mute autistic child.

An attempt was made to teach a modified version of American Sign Language to mute 5-year-old boy who had been diagnosed autistic and who had a Merrill-Palmer IQ of 65. Previous attempts to teach imitative spoken language had failed, and baseline data indicated that the child's signing vocabulary was also nonexistent. Data were collected during 20 structured sessions involving presentation of stimuli, prompting and manual guidance when necessary, and reinforcement. Continuous use of signs as communication in class and at home was emphasized. The child had mastered 12 signs at the end of the study. Spontaneous signing frequency as recorded by parents and teachers during several 48 hour periods rose from 15 to 42 emitted signs over the 3 months of the study. The child made 6 months' developmental progress during this time, as measured by a sign-language adaptation of the Alpern-Boll Communication Scale. However, the child made no apparent progress in acquiring spoken language.