Three procedures for increasing vocal response to therapist prompt in infants and children with Down syndrome.

The relative effectiveness of three procedures for increasing vocal response to prompt in 15 preschool children with Down syndrome was compared. The procedures were positive reinforcement only, positive reinforcement combined with light-dimming, and positive reinforcement combined with visual screening. All procedures produced a significant increase in percentage of response to prompt over baseline, however, light-dimming and screening, when combined with positive reinforcement, were both significantly more effective than positive reinforcement alone. Implications for increasing early vocal interaction in children with Down syndrome and other developmental delays were discussed.