A Selective Synthesis of Intervention Research for Students with Learning Disabilities

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NICHCY’s Structured Abstract 64 describes the following:

Title | A Selective Synthesis of Intervention Research for Students with Learning Disabilities

Author | Swanson, H.L., & Carson, C.

Source School Psychology Review, 25(3), 370-91.

Year Published | 1996

Abstract
Presents the selective synthesis of instructional research with children and adolescents with learning disabilities, analyzing studies across instructional domains, sample characteristics, intervention parameters, and sampling procedures. Synthesis indicates that reading is the most researched domain, and intervention studies that produce the highest effect sizes were related to derivations of cognitive and/or direct instruction.

A more detailed abstract comes from NASP, the National Association of School Psychologists, as follows:

H. L. Swanson, Cristi Carson, and Carole Sachse-Lee of the University of California, Riverside, reviewed the results of 78 studies that tested educational interventions for children with learning disabilities. They reported several findings: First, reading is the most widely researched academic area, whereas mathematics interventions are not well researched. Second, interventions that yielded the highest academic gains taught cognitive strategies, followed by those using direct instruction and remedial instruction. Third, the higher the number of intervention sessions per week, the higher the gains in academic functioning. Fourth, cognitive strategy instruction is most effective when taught within an academic domain, rather than as isolated skills. Fifth, the effectiveness of specific strategies may vary as a function the academic domain. That is, Swanson and his colleagues reported that cognitive a strategy instruction and direct instruction are the most effective interventions for teaching reading comprehension: whereas phonetic (decoding) strategy training and remedial instruction are most effective for improving word recognition and spelling skills. Cognitive strategy instruction also is effective for improving communication and language skills. School psychologists are well advised to consider such research findings when making recommendations for students with learning disabilities.  (School Psychology Review, Vol. 25, #3)

Background
In the two decades between the mid 1970’s and the mid 1990’s the number of children classified as having a specific learning disability (LD) nearly tripled. Children with LD became the largest single category of students served under special education, accounting for almost half of all the children receiving special education services. Despite the growing number of students receiving special education under the category of “specific learning disability,” the authors of this study found that questions such as, “Which intervention is best suited for students with LD?” and “Which intervention works best for which subgroup of students with LD?” could still not be answered. This meta-analysis was undertaken to answer these questions and synthesize what intervention research could tell us about effective instructional interventions for children with LD.

Research Questions

  1. Which intervention works best for which subgroup of students with LD?
  2. Do the interventions that are effective in teaching students with LD vary depending on the following factors:

Instructional domain (e.g., reading, social skills),

Sample characteristics (e.g., age, intelligence),

Intervention parameters (length of sessions, number of weeks),

Sampling procedures (e.g., random assignment to conditions vs. intact groups)?

Research Design
Meta-Analysis*

  • Number of Studies Included | 78
  • Number of Subjects | 5-59, with a mean sample size of 19.94
  • Years Spanned | 1968-1993

Research Subjects
The participants in these studies were students with learning disabilities.

Age/Grade of Subjects
The ages of subjects in the treatment groups varied from 6.5 years to 17.3 years, with a mean age of 10.64 years old. The ages in the control groups varied from 6.5 to 17.10 years, with a mean age of 10.57.

Specified Disability
Learning Disabilities (LD)

Intervention
This meta-analysis investigates a variety of interventions for students with LD. These interventions were classified into 1 of 4 models: strategy instruction and direct instruction; direct instruction alone; strategy instruction alone; neither strategy instruction nor direct instruction; for descriptions of what strategy instruction and direct instruction involve, see the “Additional Resources” section.

Duration of Intervention
The typical intervention instruction was held for 41.79 minutes, 3.64 times a week, over 4.79 weeks.

Findings

  1. Reading was the most researched domain, whereas mathematics and intellectual processing were the least researched.
  2. Intervention studies that produced the highest effect sizes were based on cognitive and/or direct instruction.
  3. No significant differences in effect sizes were found across response domains (e.g., reading, mathematics, spelling, language).
  4. Effect sizes for cognitive processes (e.g., attribution, metacognition, memory) were higher when coupled with academic domains than when “isolated” for intervention.
  5. Effect sizes were significantly higher for intact or stratified groups than for randomly sampled groups.

Combined Effects Size

  1. The analyses yielded 78 studies with a total of 324 effect sizes and a mean effect size of .85 (SD = 1.17).
  2. The mean effect size scores for various instructional orientations were:

—0.59 for eclectic approaches (approaches not directed specifically to academic skills),

—0.91 for direct instruction,

—0.68 for remedial instruction, and

—1.07 for strategy instruction

Conclusion/Recommendations
The large mean effect size suggests that a variety of instructional approaches have a significant beneficial effect on students with LD.

  • Reading instruction for students with LD is the most researched domain, with 16 studies on word recognition skills and nearly twice as many studies focused on reading comprehension. The most underrepresented domains of investigation are in the areas of mathematics, intelligence, language, perception, and memory.

This meta-analysis indicates that specific procedures are effective in certain instructional areas.

  • Effective procedures for reading comprehension, for example, are direct instruction and cognitive strategy instruction. (Sources of additional information on both of these approaches are listed under the “Additional Resources” section.)
  • Word recognition skills and spelling are most positively influenced by phonetic/decoding training.  (More information on phonetic/decoding training is available via the links provided in the “Additional Resources” section.)
  • Cognitive strategy instruction is effective in the communication-language domain.

Some domains are influenced by various treatment effects, even when they are not the main focus of the intervention.

  • For example, cognitive strategy instruction used to improve reading or writing performance may also influence measures of cognition, such as metacognition (i.e., when a learner thinks about, plans, or evaluates his or her own thinking or learning).

___________

* Meta-Analysis | A widely-used research method in which (1) a systematic and reproducible search strategy is used to find as many studies as possible that address a given topic; (2) clear criterion are presented for inclusion/exclusion of individual studies into a larger analysis; and (3) results of included studies are statistically combined to determine an overall effect (effect size) of one variable on another.

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