PROJECT SUMMARY This R03 resubmission proposes to evaluate whether the extinction bursts (i.e., temporary increases in rate or intensity of behavior during extinction) of individuals with intellectual and developmental disabilities (IDD) can be mitigated through systematic assessment and intervention. This project addresses a critical need in the assessment and treatment of severe challenging behavior for individuals with IDD because extinction is often a necessary component of effective intervention but the potential for bursts precludes its use in environments that cannot support escalations (e.g., public spaces). The Goal of this application is to identify mechanisms responsible for bursts, and to facilitate strategic extensions toward discovery for treatments of challenging behavior. AIM 1: In the service of this goal, we aim to evaluate the accuracy of an efficient alternative to demand-curve analysis (i.e., progressive ratio reinforcer analysis) in quantifying reinforcer value (i.e., Pmax). AIM 2: We also aim to evaluate the utility of manipulating baseline reinforcement parameters for controlling bursts when those manipulations are informed by the results of demand-curve analysis (AIM 2). We will enroll 80 adults with developmental disabilities in a low-stakes translational investigation employing a 2x2 factorial, crossed, and randomized matched blocks design, with batched randomization logic. Procedures will include: (a) conducting progressive ratio and progressive-fixed ratio reinforcer analyses for each study participant (AIM 1), and (b) randomly assigning each participant to one of four experimental conditions to determine whether information about reinforcer value can be used to set baseline parameters that either promote or eliminate bursts during extinction (AIM 2). This project aligns with objectives of the Intellectual and Developmental Disabilities Branch (IDDB) of the National Institute of Child Health and Human Development (NICHD) because it contributes to understanding of factors that facilitate efficient elimination of severe challenging behavior and promotes the development of treatments which can improve the behavioral health, clinical care, and qualities of lives of individuals with IDD. Specifically, the outcomes of this project promise to provide insight into the ways in which researchers can mitigate the undesirable collateral effects (i.e., extinction bursts) of therapeutic action (i.e., extinction) against severe challenging behavior. This project is appropriate for the R03 funding mechanism because it is a clearly defined study that can be completed in two years, with limited resources.