Dixon, Wiggins, Belisle (2018)


The Effectiveness of the PEAK Relational Training System and Corresponding Changes on the VB-MAPP for Young Adults with Autism


Dixon, M. R., Wiggins, S. H., & Belisle, J. (2018). The effectiveness of the peak relational training system and corresponding changes on the VB-MAPP for young adults with autism. Journal of Applied Behavior Analysis, 51(2), 321–334. https://doi.org/10.1002/jaba.448


  • Mark R. Dixon
  • Scott H. Wiggins
  • Jordan Belisle

Article Info

  • Journal of Applied Behavior Analysis (2018)
  • Volume 51, Issue 2,
    pages 321-334

Key Words

  • Autism
  • Language
  • PEAK
  • Verbal Behavior


The current investigation sought to extend prior research evaluating the use of the PEAK Relational Training System as a comprehensive treatment model in improving language skills demonstrated by individuals with autism. Baseline PEAK-Direct Training and Verbal Behavior Milestone Assessment and Placement Program (VB-MAPP) assessments were conducted across 3 adult male participants, and scores on the PEAK-Direct Training assessment were used to select targets for intervention. Language instruction guided by the PEAK-Direct Training module was implemented for 45 to 69 days across participants. Results suggest that participants mastered target skills throughout the training phase, and VB-MAPP test probes showed an increasing trend. Follow-up probes suggested that scores on the VB-MAPP maintained when training was discontinued. In addition, participants demonstrated an increase in assessment scores on the PEAK-Direct Training assessment in the follow-up phase, including the mastery of untargeted verbal skills.


The purpose of Dixon et al. (2018) was to extend the results of previous research (McKeel et al., 2015), which supported the use of PEAK-DT as a comprehensive treatment model (CTM) applied to people diagnosed with Autism. This purpose has 2 main components. First, replication of the McKeel, et al. (2015) study, through the use of a single-case design, rather than a group design used in the original study. Per McKeel, et al. (2015), the original study explored PEAK with 27 children (ages 7 to 21) diagnosed with Autism, while Dixon et al. (2018) used 3 adult males (ages 19 to 21). Only 6 of the 27 participants of the McKeel study were ages 19 to 21, the ages of the participants in the Dixon study. Second, the extension includes the use of periodically probing performance by conducting VB-MAPP assessments throughout the study to corroborate PEAK-DTA scores. As both assessments measure verbal operant development differently, the VB-MAPP can confirm comprehensive language learning as a result of PEAK-DTA.

The assessment component of the PEAK curriculum was an Assessment-to-Treatment Approach (ATA). An ATA is an approach that identifies specific deficit areas, in regard to skills such as tacting and receptive communication, that can be targeted using ABA approaches, such as discrete trial training and incidental teaching. More concisely, PEAK was used as an ATA to select the targets of interventions. An ATA can be used in both single-case and between-group research. In single-case, the goal of an ATA is for the learners to demonstrate achieving mastery criteria of the target goals. In between-group, the goal of an ATA is for learners to demonstrate mastery criteria for target goals when compared to a control group.


  • Comprehensive Treatment Models (CTM): VB-MAPP, PEAK-DTA
  • Assessment-to-treatment approach: assessments identify deficiency areas that are then directly targeted through an ABA approach
  • Purpose: extend results of previous research supporting the use of PEAK-DT as a CTM in application with individuals with autism.
    • Evaluate with adults
    • Track skill acquisition over time and probed performance on VB-MAPP
  • CTMs are branded protocols such as the VB-MAPP or PEAK assessments. They target a broad skill area, in contrast to focused intervention strategies. For example, a CTM may target language while a targeted intervention strategy may target a skill like tacting
  • Treatment models that target language and communication skills often use an assessment-to-treatment approach (Gould, Dixon, Najdowski, Smith, & Tarbox, 2011), and both single-case and between-group research have established that this approach can lead to targeted skill acquisition. In this approach, assessments are used to identify specific skill-deficient areas (e.g., tacting colors, receptively labeling animals), and ABA approaches are prescribed (e.g., discrete trial training [DTT], incidental teaching) that directly target identified skill deficits.


The results from Dixon et al (2018) showed that pre-test scores for both PEAK-DTA and the VB-MAPP were low across all 3 participants. After interventions were implemented, 1 of 3 participants mastered 19 target goals at a low, steady rate (0.28-programs/day), maintaining skill acquisitions during both PEAK and VB-MAPP post-tests. For 2 of 3 participants, target goals were mastered at higher steady rates (0.60- and 0.79-programs/day), and they maintained skill acquisitions across both PEAK and VB-MAPP post-tests.