The Effects of Pivotal Response Training on Reciprocal Vocal Contingency in Children with Autism Spectrum Disorder

Background: Pivotal response treatment (PRT) is a naturalistic developmental behavioral intervention for children with autism spectrum disorder (ASD) that targets “pivotal” skills (e.g., motivation and responsivity) to facilitate broad changes across functional skills. Combining clinician-delivered and parent-implemented pivotal response training as a package treatment (PRT-P) may increase the program’s effectiveness for children with autism spectrum disorder (ASD). Reciprocal vocal contingency (RVC), an automated measure of vocal reciprocity, may provide more internally-valid evidence of the effects of PRT-P relative to parent report and parent-child interaction session measures, which are at risk for over-estimating children’s skills in the PRT-P group relative to the control group. Due to its automatic derivation, RVC is at low risk of bias and feasible for clinical use. Additionally, RVC is designed to be independent of chance sequencing of events. The more frequently children and adults vocalize, the more their vocalizations will be adjacent by chance. In children with ASD, past studies have shown that RVC continues to be construct valid as a measure of reciprocity, even after controlling for base rates of child and adult vocalizations. In contrast, its primary competitor as a putative measure of “vocal reciprocity” (i.e., number or rate of vocal turn-taking) ceases to show convergent validity after controlling for the base rates of child and adult vocalizations.

Objectives: To examine whether participants in the PRT-P group have higher ranked RVC values than participants in the control group after 12 and 24 weeks of intervention.

Methods: Forty-eight children with ASD (29 to 71 months old) were randomly assigned to either the PRT-P or business as usual control group. Data for the current analysis were available for 40 participants. The PRT-P included weekly individual parent training sessions and 10 hours per week of in-home intervention for 12 weeks, followed by 12 additional weeks of monthly parent training sessions and 5 hours per week of in-home intervention. For each participant at each of three measurement periods (pre, mid-intervention phase, and posttest, separated by 12 weeks each), we quantified RVC from two daylong vocal samples using a computer program to organize the data for subsequent three-event sequential analyses that calculated the degree to which children responded to adult vocal responses to children’s immediately preceding vocalizations.

Results: Although the group differences were non-significant at baseline (Time 1; p = .12) and after 12 weeks of intervention (Time 2; p = .25), children in the PRT-P group had higher ranked RVC scores than children in the control group after 24 weeks of intervention (Time 3; U = 125, p = .048). The percentage of all possible pairwise comparisons for which the PRT-P group exceeded the control group was 69%, which is a moderate effect size.

Conclusions: These findings support the effectiveness of PRT-P on vocal reciprocity of children with ASD, which may be a pivotal skill for language development. Continued investigation is required to determine the specific time range and developmental level for which RVC is most useful.