[Therapy of speech development delay in mentally retarded children].

Twenty-one mentally retarded children participated in 40 language training sessions each that were based on behavior therapy. The training program had four levels of difficulty. The appropriate level for a given child was determined by evaluation of the child's spontaneous speech. Of the 21 children, 8 started with a 6-week waiting period. During this time they had 40 sessions of occupational therapy. The effect of the waiting period and of therapy on the children's speech was assessed by analysis of spontaneous verbal utterances and by specially constructed imitation tests. The children were tested before the waiting period and before and after therapy. Whereas the waiting period by itself had no significant effect, the therapy led to a significant increase in the mean length of utterances (in morphemes) and to highly significant improvement on the imitation tests.