Effects of video based training on spoken and signed language acquisition by students with mental retardation.

The purpose of this study was to assess the effects of video presentations on the acquisition of both spoken and manually signed lexical items by students with mental retardation. A 10-lesson curriculum in which lexical items were introduced and reviewed by one of three pedagogical methods (therapist only, therapist plus video, or video only) was implemented over a four week period. Pretest and posttest measures of expressive and receptive vocabulary of 35 students with mental retardation revealed that all three methods resulted in significant increases in both spoken and manual sign production of the targeted lexical items compared to control items which were not taught. The therapist only and therapist plus video methods yielded significantly higher sign production scores than the video only method. Receptive vocabulary was not significantly improved by the intervention.