The effects of mands and models on the speech of unresponsive language-delayed preschool children.

The effects of the systematic use of mands (non-yes/no questions and instructions to verbalize), models (imitative prompts), and specific consequent events on the productive verbal behavior of three unresponsive, socially isolate, language-delayed preschool children were investigated in a multiple-baseline design within a classroom free play period. Following a lengthy intervention condition, experimental procedures were systematically faded out to check for maintenance effects. The treatment resulted in increases in total verbalizations and nonobligatory speech (initiations) by the subjects. Subjects also became more responsive in obligatory speech situations. In a second free play (generalization) setting, increased rates of total child verbalizations and nonobligatory verbalizations were observed for all three subjects, and two of the three subjects were more responsive compared to their baselines in the first free play setting. Rate of total teacher verbalizations and questions were also higher in this setting. Maintenance of the treatment effects was shown during the fading condition in the intervention setting. The subjects' MLUs (mean length of utterance) increased during the intervention condition when the teacher began prompting a minimum of two-word utterances in response to a mand or model.