The Autism Society Event and Education Recordings Archive

The Stimulus Control Ratio Equation (SCoRE) is a metric to summarize a behavioral repertoire by comparing the relative frequency of its component parts. The SCoRE compares observed proportions of responding against the null hypothesis to yield a statistic to describe the present level of functional performance. Such information may be useful for measuring change over time and comparing treatment effects within individuals and across groups. Presently, we describe the procedures for conducting this analysis, and demonstrate two applications of the SCoRE as it applies to both verbal behavior and derived responding. The SCoRE is a pragmatic methodology for summarizing composite verbal repertoire by comparing the relative frequency of its component parts. The literature-base on verbal behavior interventions primarily addresses four verbal operants: mand, echoic, tact, and intraverbal. The convergent control of these relations over the behavior of the speaker was described by Michael, Palmer, and Sundberg (2011). However, such interdependence is premised upon the functional independence of each. Indeed, Sundberg’s (2007) VB-MAPP data show that adept speakers respond at approximately equivalent rates across these four primary operants. Consequently, we postulate that proportional levels of stimulus control to induce each of the primary verbal operants are a prerequisite to fluent verbal behavior. In contrast, the verbal behavior of speakers who exhibit dependent stimulus control - in which, for example, mands, tacts, and intraverbals are emitted only with the support of an echoic stimulus - may be described as “autistic” or otherwise incommensurate (Drash & Tudor, 2004). Summarizing the relative response rates of individual verbal operants through the SCoRE provides a statistic for comparison within and across individuals. In addition to idiographic progress monitoring, the SCoRE has applications for use in clinical trials or other group comparisons for demonstrating treatment efficacy as a pre- and post-measure. Compared to many of the structured descriptive assessments that are commonly used to measure verbal behavior, the advantages of experimental analysis employed by the SCoRE include its objectivity, efficiency, and quantitative precision. Furthermore, the pragmatic nature of the SCoRE protocol allows for sufficient flexibility to be conducted across a variety of settings, including clinical, educational, and residential. Given that the ultimate purpose of any science is to describe events in familiar terms, the SCoRE provides a mechanism for doing just that. The SCoRE metric can be interpreted analogous to Pearson’s product-moment correlation coefficient, in which the complexity of the repertoire is observed between zero and one. Consequently, it may be appropriate to use Ferguson’s (2009) thresholds for interpreting the “size” of the repertoire. Below .20, we might refer to an individual’s verbal repertoire as emergent. Greater than or equal to .20, we can describe to the repertoire as practical. A moderate repertoire refers to a SCoRE at or above .50. And greater than or equal to .80, we can describe to the repertoire as strong. Attendees of this session will be able to: (1) identify the primary verbal operants, (2) describe convergent control over language, (3) conduct and verbal operant analysis, and (4) calculate the SCoRE.