| Abstract: |
Several previous studies have shown that when expressive signing is trained using simultaneous communication, in which both visual and spoken cues may function as discriminative stimuli for signing, children with severe mental retardation demonstrate overselectivity, usually to the visual modality. As a result, such children fail to acquire other language functions, such as speech comprehension, despite the many occasions during training that words and their referents co-occur. We report two studies, both of which used alternating treatments designs to assess the relative efficacy of two methods of overcoming overselective attention during simultaneous communication training. The first method, Extensive Sign Training, involved overtraining expressive signing in simultaneous communication, but with a reduced reinforcement schedule. The second method, Mediated Sign Training, involved training receptive speech functions prior to simultaneous communication training. In both studies, the Extensive condition produced faster acquisition of expressive signing than the Mediated condition. Contrary to previous research, however, the Extensive training procedure used in both studies failed to overcome overselectivity, and thus to facilitate speech comprehension. |
