Evidence Based Education
Dyslexia Interventions
The National Reading Panel meta-analysis is often cited for being of value in discussions of dyslexia instruction. However, the majority of the paper was focused on core instruction and not the instruction of dyslexic students. In September of 2022, a meta-analysis was specifically conducted on the topic of interventions for dyslexic or at risk students, by Colby Hall, et al. In my opinion, this paper helps to answer some of the most important questions in the science of reading to date.
The meta-analysis looked at 53 experimental or quasi-experimental studies of interventions for dyslexic or at risk readers, dating between 1997 and 2020. The study found a mean weighted hedge’s g effect size of .33 overall and showed strong fixed moderator effects for the impact of time on outcomes. However, they also broke down their results across many different factors and study designs, using a random effects model, as can be seen below:
What Does This Study Prove:
This study is incredibly important not just because it provides the most up to date synthesis of the research on the topic, but because it helps to answer some very important research questions that existed. Firstly, this meta-analysis shows that students with dyslexia are best helped earlier than later. Of course this is not surprising, but it helps to reinforce the idea that early intervention is not just helpful but ESSENTIAL.
This study showed the strongest benefits for interventions that included phonemic awareness (PA) instruction, suggesting that PA instruction might be the most important type of instruction for dyslexic students. This supports Dr. Kilpatrick's assertion that dyslexia is primarily a disorder relating to students phonemic awareness skills and that dyslexia tutors should therefore spend more time on PA instruction. That being said, this cannot be taken as evidence for oral only PA instruction, as the meta-analysis did not break down the results of studies that included PA with phonics or without. Nor did the study specifically control for whether or not phonics was included in each intervention.
This meta-study also looked at whether or not adding morphological instruction benefited dysexlic or at risk students. As I pointed out in my secondary meta-analysis on morphology instruction, previous meta-studies have shown a very high effect for providing morphology instruction to at-risk readers. However, those results were based on a limited number of studies. This meta-analysis looked at 29 studies that included morphology/vocabulary and compared them with 28 studies that did not. They found no statistically significant difference for including or not including morphology/vocabulary instruction, for dyslexic or at risk readers.
This meta-analysis also looked at whether or not spelling instruction was included within the intervention. They found a very significant benefit for including spelling instruction over not including spelling instruction. This matches previous research on the topic and helps to demonstrate that spelling instruction is an essential component in proper reading instruction.
The meta-analysis looked at the difference for including vs not including multi-sensory instruction. They found multisensory instruction significantly lowered outcomes for dyslexic and at risk readers. This is in line with the findings of the 2021 Elizabeth Steven’s meta-analysis of the topic, and my sub-analysis of the topic. This meta-analysis further suggests that multisensory instruction does not increase the results for dyslexic learning outcomes. However, it should be said that of the 53 studies included only 4 did not contain a multi-sensory component, suggesting that this effect size is less reliable. It also suggests that we desperately need more research on this specific topic.
In general this meta-analysis showed that for dyslexic students:
-Early intervention is essential
-PA instruction is essential
-Spelling Instruction is essential
Written by Nathaniel Hansford
Last Edited 2022-09-25
References:
Hall, C., Dahl-Leonard, K., Cho, E., Solari, E.J., Capin, P., Conner, C.L., Henry, A.R., Cook, L., Hayes, L., Vargas, I., Richmond, C.L. and Kehoe, K.F. (2022), Forty Years of Reading Intervention Research for Elementary Students with or at Risk for Dyslexia: A Systematic Review and Meta-Analysis. Read Res Q. https://doi.org/10.1002/rrq.477
Stevens EA, Austin C, Moore C, Scammacca N, Boucher AN, Vaughn S. Current State of the Evidence: Examining the Effects of Orton-Gillingham Reading Interventions for Students With or at Risk for Word-Level Reading Disabilities. Except Child. 2021 Jul;87(4):397-417. doi: 10.1177/0014402921993406. Epub 2021 Feb 22. PMID: 34629488; PMCID: PMC8497161.
Graham, S., & Hebert, M. (2011). Writing to read: A meta-analysis of the impact of writing and writing instruction on reading. Harvard Educational Review, 81(4), 710-744. https://doi.org/10.17763/haer.81.4.t2k0m13756113566
N, Hansford. (2022). Morphology Instruction: A Secondary Meta-Analysis. Teaching by Science. Retrieved from <https://www.pedagogynongrata.com/morphology>.
N, Hansford. (2022). Multi-Sensory Instruction. Teaching by Science. Retrieved from <https://www.teachingbyscience.com/multi-sensory>.