Children with autism spectrum disorder (ASD) often develop rigid, repetitive language patterns. Although discrete-trial training effectively establishes intraverbal responses—verbal behavior controlled by another's verbal stimuli—it frequently produces stereotyped sequences. In the present case, a fixed emission order (e.g., carrot → cabbage → eggplant for 'vegetables') led to blended utterances in which phonemes from adjacent words merged into a single unit, necessitating intervention. This study examined whether combining a Lag 1 schedule with differential reinforcement of orders differing from the baseline sequence (DRDO) could increase response-order variability in a 12-year-old boy with ASD and severe intellectual disabilities.A multiple-baseline-across-behaviors design was employed across five semantic categories (fruits, vegetables, animals, insects, vehicles). Following baseline and instruction phases—during which instructions to vary response order produced no change—variability training was introduced sequentially. Two dependent variables were recorded: (A) proportion of words emitted in a different order than the preceding trial, and (B) proportion differing from the baseline sequence.The Lag 1 alone produced minimal improvement. Adding DRDO—reinforcing sequences differing from the baseline order—substantially increased both measures in the first category (Non-overlap of All Pairs = 1.00; Improvement Rate Difference = 1.00 for measure A; NAP = 0.94, IRD = 0.88 for measure B). Gains generalized rapidly; later-trained categories reached criterion within one to three training trials, suggesting cross-category transfer. The classroom teacher responded positively on a 15-item social validity questionnaire. These findings suggest DRDO is an effective adjunct when instruction or Lag alone are insufficient, and offer a classroom-feasible framework for sequencing interventions.

Authors:
Masashi Kawamura, Hachioji City Utsukidai Elementary School, Japan

About the Presenter(s)
Masashi Kawamura, Ph.D. Senior Teacher at Utsukidai Elementary School. Interests: ABA and Special Education. Current Project: Training in language and communication skills for children with autism spectrum disorder and intellectual disabilities.

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