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Using Pattern of Strengths and Weaknesses to Identify Specific Learning Disabilities

A Pattern of Strengths and Weaknesses (PSW) is one of three legal methods K-12 schools can use to determine when a child or adolescent qualifies for a Specific Learning Disability (SLD) label and for services under an Individual Educational Plan (IEP). The other two allowed methods are IQ-Achievment Discrepancy (the student’s achievement in reading writing, or math is significantly lower than their IQ) and Response to Intervention (RTI; failure to response indicates SLD). PSW has several advantages over the other two methods which is why school districts in many U.S. continue to adopt PSW as their primary method.

The Advantages of Using PSW Include

  • Earlier identification and access to services – no need to wait for the learner’s achievement to become significantly lower than their IQ.
  • A better understanding of why the learner is struggling to acquire certain academic skills, such as reading.
  • Reduced frustration with learning – the student does not need to endure months or more of frustration with instruction and interventions that are not working.

How PSW Works

IDEIA 2004 Federal regulations allow the use of a pattern of strengths and weaknesses (PSW) to identify a specific learning disability (SLD). The PSW approach, known as “the third method”, allows the use of a pattern of strengths and weaknesses in achievement, cognitive abilities, or both. PSW methods assume that one or more cognitive ability or processing weaknesses underlie SLD. The occurrence of significant cognitive processing weaknesses within a learner who displays otherwise normal cognitive abilities or some cognitive strengths is viewed as a strong indication of SLD (see the left side of the triangle in the figure above). A PSW within achievement is also a consideration (see the right side of the triangle in the figure above).

When an achieivement area is deficient and one or more related cognitive processes are significant weaknesses, this is considered evidence for “consistency.” That is, the PSW model considers more than just strengths and weaknesses, but also examines whether there are matches between a low area of achievement and low cognitive processes that are the best predictors of that type of achievement (See the bottom of the triangle in the figure above.) (See the PSW Cognitive-Processes Achievement Chart.) (Also, see a PSW sample report for how PSW analysis can identify SLD.) John, this would be the PPA sample report.

Research Supporting PSW

Using PSW to identify SLD is legally defensible and evidence-based. Research in education, neuroscience, and related fields provides extensive support for using a PSW in cognitive processes to identfity specific learning disabilities. In a review of the research, Hale, Chen, Tan, Poon, & Fitzer, (2016) found that “Children with disabilities have varying deficits in attention, phonological, orthographic, rapid naming, long-term memory, memory encoding/retrieval, fluid reasoning, spatial processing, receptive/expressive language, psychomotor skills, response inhibition, working memory, processing speed, and executive function relative to typical children.” A meta-analysis of 32 studies by Johnson, Humphrey, Mellard, Woods, & Swanson (2010) found “moderately large to large effect sizes in cognitive processing differences between groups of students with SLD and typically achieving students.” The processes included were working memory, short-term memory, phonological processing, processing speed, executive function, and language.

Research has also identified strong relations between specific areas of achievement and specific cognitive processes (Flanagan, Ortiz, & Alfonso, 2013; McGrew & Wendling, 2010; Naglieri, 2011). For instance, the development and performance of basic reading skills depends heavily on long-term memory, oral language, orthographic processing, phonological processing, processing speed, and working memory (Dehn, 2014).

PSW Models

There are four main PSW models. Each includes criteria for evaluating cognitive and academic performance that, when met, indicate a PSW that is consistent with SLD. Although the conceptual definition of PSW is agreed upon by all proponents of PSW, the criteria they propose vary somewhat. All PSW models follow a multi-source/multi-method assessment approach to comprehensive evaluations for SLD determination. All PSW proponents also agree that having information about the cognitive processing weaknesses that are likely interfering with basic skill acquisition and development is critical when multi-disciplinary teams meet to determine appropriate and targeted interventions and supports for students.

The Four PSW Models

When schools use a PSW approach to identify SLD, it is recommended that they use analytical software so that decisions are based only on strengths and weaknesses that have statistical significance. Consistencies between achievement and related processes should also be identified statistically. For more details on these methods see (Insert link to the PSW laminate).

  • The Discrepancy/Consistency Method (DCM) is based on a systematic examination of cognitive and academic achievement test scores. The DCM is conceptual and could be used with any measure of psychological processes but has been associated with the PASS (Planning, Attention, Simultaneous, Successive) theory. Jack Naglieri is the proponent of this model (https://jacknaglieri.com/).
  • The Core-Selective Evaluation Process (C-SEP) is a focused and data-driven assessment and analysis method informed by contemporary cognitive theory and driven by clinical judgment. This is a more informal approach to PSW that is primarily used in Texas (https://csep.online/index.html).
  • The Dual Discrepancy/Consistency (DD/C) method is based on Cattell-Horn-Carroll (CHC) theory and applies a cross-battery analysis method known as X-BASS (https://wiley.com/go/XBASS).
  • Dehn’s PSW model uses software known as The Psychological Processing Analyzer (PPA) to analyze standardized test scores for statistically significant strengths and weaknesses among 14 neuropsychological (cognitive) processes and among 8 areas of achievement. Details on Dehn’s PSW model can be found in Essentials of Processing Assessment, 3rd Edition.

Dehn’s Psychological Processing Analyzer (PPA)

The Psychological Processing Analyzer (PPA) identifies statistically significant strengths and weaknesses among 14 cognitive processes and 8 areas of achievement, and then compares cognitive processes with closely related areas of achievement. The primary purpose of the PPA is to assist the professional user with the statistical analysis of test scores that have been obtained through selective, multi-battery testing and to assist with the idenfication of SLD.

According to Dehn’s PSW model, psychological (cognitive) processing assessment data supports the diagnosis of an SLD when all of the following occur:

  1. At least one psychological process is identified as a statistically significant, intra-individual weakness.
  2. There is at least one processing strength. Ideally, there should be a statistically significant intra-individual strength, but a processing score within the average range may be considered a strength.
  3. A low area of achievement being considered for SLD should have at least one intra-individual processing weakness associated with it, and these processing and achievement areas should have a strong research-based relation.
  4. There should be consistency between the processing intra-individual weakness score and the related area of achievement being considered for SLD. That is, they should both be low scores, or the process score could be lower than the achievement score.
  5. In agencies where a PSW in achievement is required, there should also be a statistically significant intra-individual weakness in the area of achievement being considered for SLD identification.

How Dehn’s Model Differs From DD/C Model

The DD/C Model is based on the CHC broad abilities. Dehn’s model goes beyond CHC by incorporating other important cognitive abilities that are necessary for the acquisition of skills in reading, math, and writing. These additions include attention, executive functions, fine motor, oral language, phonological processing and orthographic processing. Dehn’s model emphasizes psychological and cognitive processes that are highly related with academic learning, regardless of whether they are classified as narrow or broad abilities by CHC theory (link to the PSW Processes-Achievement chart).

Psychological/Cognitive Processes Included in Dehn’s Model and the PPA

  • Attention (AT)
  • Auditory Processing (AP)
  • Executive Functions (EF)
  • Fine Motor (FM)
  • Fluid Reasoning (FR)
  • Verbal Long-Term Recall (VLTR)
  • Visual-Spatial Long-Term Recall (VSLTR)
  • Oral Language (OL)
  • Phonological Processing (PP)
  • Processing Speed (PS)
  • Visual-Spatial Processing (VSP)
  • Orthographic Processing (OP)
  • Verbal Working Memory (VWM)
  • Visual-Spatial Working Memory (VSWM)

Features and Benefits of Dehn’s Psychological Processing Analyzer (PPA)

  • Statistically analyzes scores from more than 80 different test batteries
  • For use with selective, multi-battery testing of psychological processes
  • Analyzes strengths and weaknesses across 14 psychological/cognitive processes
  • Analyzes strengths and weaknesses across 8 SLD achievement areas
  • Ideal for identifying the Pattern of Strengths and Weaknesses (PSW)
  • Identifies achievement scores that are consistent with processing weaknesses
  • Allows unlisted composite and subtest scores to be entered
  • Allows a cognitive ability composite score to be used as the predictor
  • Includes report with narrative, graph, observations, and recommendations
  • Saves scores and reports that can be edited later
  • Includes tests administered in Spanish
  • Can be used with Dyslexia evaluations

Purchasing the PPA Software

Two-year individual licenses or five-year site licenses are available. Each includes an unlimited number of cases and reports.
Follow this link more information on or to purchase the Psychological Processing Analyzer (PPA).
The above link leaves this website and goes to the PPA information page on Schoolhouse Educational Services, Inc. website

Ventura County PSW Resource

For schools looking to implement PSW, a great resource can be found the Ventura County SELPA website (Ventura County Office of Education)