An evaluation of the relationship between receptive speech skills and expressive signing.

We examined the effects of receptive speech on the acquisition of manual signing among three mentally retarded children. In an alternating treatments design, we compared the acquisition of expressive signs that were, versus were not, in a child's receptive vocabulary. The children were trained via total communication in which pictorial referents were named during sign training. Signs corresponding to known words were generally acquired faster and retained better than signs corresponding to unknown words. We conducted posttests to assess the stimulus control of signing and any changes in expressive and receptive signing and speech. Observed changes in performance could be accounted for by attention to aspects of the stimulus complex during training and functional equivalence of stimuli established by training.