Enhancing Practice through Application of Cattell–horn–carroll Theory and Research: a “third Method” Approach to Specific Learning Disability Identification

This article demonstrates how the broad and narrow abilities and processes that comprise Cattell – Horn – Carroll (CHC) theory and their relations to specific academic outcomes have begun to transform our current understanding of the definition of and methods for indentifying specific learning disability (SLD), particularly in the school setting. The manner in which CHC theory has been used to guide evaluation of the academic and cognitive capabilities of students who are suspected of having SLD is described. Current psychometric methods for identifying SLD that have a foundation in CHC theory are highlighted. These newer methods are based on what is known as the “third method,” a provision for SLD identification included in the federal regulations (34 CFR 300.540-543) accompanying the Individuals with Disabilities Education Improvement Act that permits the use of alternative, research-based approaches. A method based on an integration of existing third-method approaches, called the Hypothesis-Testing CHC Approach (HT-CHC), was proposed. The HT-CHC method is expected to be carried out within the context of a Response to Intervention (RTI) service delivery model. Benefits of this approach over ability – achievement discrepancy and RTI-only methods and future directions in SLD identification research are discussed.