When IDEA was last reauthorized in 2024, additional methods of specific learning disability (SLD) identification were added. For decades, SLD identification was determined by a discrepancy between intellectual ability as measured by an IQ score, and academic achievement.
IDEIA, the legislation that reauthorized IDEA in 2004, stated that states had to adopt criteria for SLD identification but noted states “…must not require the use of a severe discrepancy between intellectual ability and achievement…”. The legislation goes on to note that must permit the use of a process based on the child’s response to scientific, research-based intervention, and that they may permit the use of other alternative research-based procedures for determining whether a child has a specific learning disability.”
As a result of these changes, three methods of SLD identification are used across the United States and U.S. territories.
Ability Achievement Discrepancy
Because learning disabilities often present as difficulty acquiring academic skills despite evidence of typical intelligence, Ability Achievement Discrepancy (AAD) was a preferred method of SLD identification for many decades. AAD defines an SLD as a discrepancy between an overall intellectual ability score (IQ) and academic achievement. This method typically identifies students with average or better overall cognitive ability and below average academic skills. Specific cognitive processing skills are not necessarily identified.
When AAD is used, students with low or below average over cognitive ability often are not identified because their skills are viewed as commensurate with their overall abilities. This method does not consider that overall cognitive scores (IQ scores) are impacted by specific processing deficits.
This is problematic because students with SLD frequently have weaknesses in abilities such as working memory or processing speed and these weaknesses can depress the overall IQ score as this score is essentially a composite of all the discrete cognitive abilities that are measured on these tests. Also problematic is that there is no consistent criteria for what represents a ‘significant’ or ‘severe’ discrepancy. In fact, how this is defined frequently varies from state to state and sometimes even from school district to school district.
Response to Intervention
Identification of an SLD using “a process based on the child’s response to scientific, research-based intervention” is referred to as RTI. More recently, the term multi-tiered system of supports (MTSS) has become common. As the name implies, this method provides students with increasingly intensive academic intervention and monitors the students’ response. Students who fail to show ‘adequate’ response can then be identified with an SLD.
RTI typically identifies students who are at the lowest end of the academic skill distribution. Cognitive abilities and processing skills are not assessed other than a rule out of intellectual disability. Thus, in many schools where this method of identification is approved by the state, an evaluation for an SLD may not include any formal assessment by a school psychologist or diagnostician.
While RTI has now been in use as an identification method, there is little research that defines exactly what criteria should be used to determine that a student’s progress is not adequate. Another concern with this method is that many schools and districts lack the resources to provide the training and materials to implement RTI models with fidelity.
Patterns of Strengths and Weakness
In the twenty years since the 2004 reauthorization of IDEA, patterns of strengths and weakness (PSW) models have come to be known as the “third method” of SLD identification allowed for because they are “alternative, research-based procedures” or models of SLD identification. PSW models involve the use of cognitive assessment data to document a pattern of cognitive strengths and weaknesses that are consistent with the academic underachievement the individual is presenting.
Like AAD, PSW models investigate underachievement that is unexpected given the individual’s otherwise average or typical cognitive abilities. Unlike AAD, PSW models recognize that there are numerous cognitive abilities and processing skills that are able to be assessed discreetly.
PSW models recognize that cognitive processing weaknesses will impact achievement and may also result in composite IQ scores that underestimate an individual’s potential. Neurocognitive research continues to increase our understanding of how cognitive processing abilities are best conceptualized, measured and how they impact academics.
Because “psychological processing” deficits have long been considered a core feature of learning disabilities, LDA endorses PSW models of SLD identification.
For Further Reading:
LDA’s Core Priniciples: The Best Use of Cognitive Assessment in Learning Disability Identification
LDA’s Core Principles: Response to Intervention (RTI)
LDA’s Core Principles: Evaluation and Identification of Learning Disabilities
LDA’s Specific Learning Disability Evaluation Principles and Standards
