Can my child talk? Evidence for the Emergence of Vocals in Non-Vocal Children with Autism
Children with autism exhibit significant delays in speech production and most require highly specialized training (Harlaar et al., 2008; Rutter 1985).
A variety of technologies such as echoic training (Koegel et al, 1998), antecedent rapid motor imitation (Ross & Greer 2003), stimulus-stimulus pairing (Sundberg, et al.1996) have been used for inducing vocalizations in children with autism. The current study spanning 6 years 8 months reviewed technologies developed for emergence of speech in non-vocal children with autism. A total 144 children were selected of whom 126 met the inclusion criteria and completed the study. Non-vocal children between ages 1.4-13.5 years participated in four experiments that used delayed multiple baseline design across subjects. Mastery criteria for vocalization for each participant was n=7 first instances of speech.
Experiment 1 studied the role of stimulus-stimulus pairing (SSP) during sign-mand training on vocal emergence in 58 participants of whom 83% acquired vocal status. Experiment 2 studied the effect of prompt-delays during sign-mand training on 3 children who failed to acquire vocals on experiment 1 for 9-33 weeks. Introduction of prompt-delays were effective in inducing vocals in all three children. Experiment 3 studied the additive effect of intraverbal training with paired auditory stimulus on 46 children who failed to acquire vocals after 12-40 weeks of sign-mand training and SSP. Results showed 80% children emerged with vocals after the introduction of intraverbal training. In Experiment 4 sign-mand training and intraverbal training with SSP were introduced together in 19 children. Results suggested 89% children emerged with vocals. Of the total 126 children across all experiments 105 emerged with vocals meeting the mastery criteria with permanent effects.
Across all experiments mean IOA of the study was 89% (range 83%-94%) and treatment integrity 86% (range 57%-100%). Retrospective data analysis suggested age of children was not a determinant for vocal acquisition and first instances of speech emerged across various verbal operants such as mands, echoic mands, echoics and intraverbals. Motivating operations accounted for 65% of initial vocals however 27% first vocals also emerged as intraverbal fill-ins. Time to vocalization, type of vocal emergence and relative successes of the technologies used are explored in this study.
Keywords: Vocalization, Autism, Time-Delay, Intraverbal training, Mand training, Stimulus-stimulus pairing, First instances of speech, inducing speech, Motivating Operations