Middle Eastern Journal of Disability Studies
Middle Eastern Journal of Disability Studies
Volume 16 - Vol 16, 2026
MEJDS (2026) 16: 9 |
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Ethics code: IR.IAU.SHK.REC.1402.151
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Khazandarloo L, Ahmadi R, Ghazanfari A. The Mediating Role of Information Processing Speed in the Relationship Between Working Memory and Dyslexia Symptoms in Second-Grade Primary School Children. MEJDS 2026; 16 :9
URL: http://jdisabilstud.org/article-1-3648-en.html
URL: http://jdisabilstud.org/article-1-3648-en.html
1- Department of Psychology, Shk.C., Islamic Azad University, Shahrekord, Iran
Abstract: (32 Views)
Background & Objectives: Dyslexia is one of the most prevalent learning disorders among primary school children, characterized by persistent difficulties in reading, word decoding, and reading fluency. This disorder can adversely affect academic performance, self–confidence, and social relationships. Defined as a specific learning disorder, dyslexia is a characterized by persistent difficulties in acquiring reading skills, irrespective of general intelligence level or educational opportunities. Although dyslexia is primarily classified as a linguistic disorder, emerging research evidence indicates that it is rooted in multifactorial deficits, including cognitive and neuropsychological processes. Previous studies have indicated that cognitive factors, such as working memory and information processing speed, contribute to the manifestation of dyslexic symptoms. However, the mediating role of information processing speed in the relationship between working memory and dyslexia has received limited attention, particularly in the context of the Persian language, which has distinct phonological and orthographic characteristics. This study aimed to investigate the mediating role of information processing speed in the relationship between working memory and dyslexia symptoms in second–grade primary school children.
Methods: The present study employed a cross–sectional correlational design to examine the relationships between the exogenous variable (working memory), the mediating variable (processing speed), and the endogenous variable (dyslexia). The statistical population consisted of all male and female students in the fourth to sixth grades who were referred to learning disability educational and rehabilitation centers in Tehran due to reading difficulties during the 2023–2024 academic year. These specific grade levels were selected to ensure that students possessed the cognitive maturity required to respond to the research instruments. A purposive sample of 300 students (150 girls and 150 boys) was selected. Inclusion criteria for participants were as follows: student willingness and assent to participate; written informed consent provided by parents; enrollment in the fourth to sixth grades; poor reading performance as reported by teachers; normal IQ (a score of 85 or above on the Wechsler Intelligence Scale for Children–IV); a score at least two standard deviations below the mean on the Reading and Dyslexia Test (NEMA); absence of significant physical or motor disabilities; no use of psychiatric medication; and the absence of sensory (visual or auditory) impairments or speech and language disorders. Exclusion criteria included the presence of other emotional–behavioral disorders, such as attention–deficit/hyperactivity disorder (ADHD); withdrawal of consent to participate; and cultural or linguistic barriers (i.e., difficulties stemming from accents or proficiency deficits in Persian vocabulary and grammar). The research instruments included the Reading and Dyslexia Test (NEMA) (Kormi Nouri & Moradi, 2005), the Dyslexia Checklist (Azizian & Abedi, 2004), and the Wechsler Intelligence Scale for Children–IV (Wechsler, 2003). Data were analyzed using both descriptive and inferential statistics. Descriptive statistics included frequency, percentage, minimum and maximum scores, mean, standard deviation, skewness, and kurtosis. At the inferential level, Pearson correlation coefficient and Structural Equation Modeling (SEM) were conducted using SPSS (version 28) and AMOS (version 24). The significance level for all statistical tests was set at 0.05.
Results: The findings indicated that working memory had a direct effect on dyslexia symptoms (β=–0.37, p<0.001), with higher working memory capacity associated with reduced dyslexic symptoms. The direct effect of information processing speed on dyslexia symptoms was also significant (β=–0.55, p<0.001), indicating a stronger influence than working memory. Additionally, information processing speed partially mediated the relationship between working memory and dyslexia symptoms (β=–0.25, p=0.003). Model fit indices (SRMR=0.076, NFI=0.89, GFI=0.93, CFI=0.88, IFI=0.93, χ²/df=3.98) indicated a good model fit. The coefficient of determination (R²=0.62) suggested that working memory and information processing speed explained 62% of the variance in dyslexia symptoms.
Conclusion: Based on the research findings, working memory and information processing speed play significant roles in the symptoms of dyslexia among children in the second–grade primary school. Strengthening working memory can lead to improved information processing and, consequently, a reduction in reading difficulties.
Methods: The present study employed a cross–sectional correlational design to examine the relationships between the exogenous variable (working memory), the mediating variable (processing speed), and the endogenous variable (dyslexia). The statistical population consisted of all male and female students in the fourth to sixth grades who were referred to learning disability educational and rehabilitation centers in Tehran due to reading difficulties during the 2023–2024 academic year. These specific grade levels were selected to ensure that students possessed the cognitive maturity required to respond to the research instruments. A purposive sample of 300 students (150 girls and 150 boys) was selected. Inclusion criteria for participants were as follows: student willingness and assent to participate; written informed consent provided by parents; enrollment in the fourth to sixth grades; poor reading performance as reported by teachers; normal IQ (a score of 85 or above on the Wechsler Intelligence Scale for Children–IV); a score at least two standard deviations below the mean on the Reading and Dyslexia Test (NEMA); absence of significant physical or motor disabilities; no use of psychiatric medication; and the absence of sensory (visual or auditory) impairments or speech and language disorders. Exclusion criteria included the presence of other emotional–behavioral disorders, such as attention–deficit/hyperactivity disorder (ADHD); withdrawal of consent to participate; and cultural or linguistic barriers (i.e., difficulties stemming from accents or proficiency deficits in Persian vocabulary and grammar). The research instruments included the Reading and Dyslexia Test (NEMA) (Kormi Nouri & Moradi, 2005), the Dyslexia Checklist (Azizian & Abedi, 2004), and the Wechsler Intelligence Scale for Children–IV (Wechsler, 2003). Data were analyzed using both descriptive and inferential statistics. Descriptive statistics included frequency, percentage, minimum and maximum scores, mean, standard deviation, skewness, and kurtosis. At the inferential level, Pearson correlation coefficient and Structural Equation Modeling (SEM) were conducted using SPSS (version 28) and AMOS (version 24). The significance level for all statistical tests was set at 0.05.
Results: The findings indicated that working memory had a direct effect on dyslexia symptoms (β=–0.37, p<0.001), with higher working memory capacity associated with reduced dyslexic symptoms. The direct effect of information processing speed on dyslexia symptoms was also significant (β=–0.55, p<0.001), indicating a stronger influence than working memory. Additionally, information processing speed partially mediated the relationship between working memory and dyslexia symptoms (β=–0.25, p=0.003). Model fit indices (SRMR=0.076, NFI=0.89, GFI=0.93, CFI=0.88, IFI=0.93, χ²/df=3.98) indicated a good model fit. The coefficient of determination (R²=0.62) suggested that working memory and information processing speed explained 62% of the variance in dyslexia symptoms.
Conclusion: Based on the research findings, working memory and information processing speed play significant roles in the symptoms of dyslexia among children in the second–grade primary school. Strengthening working memory can lead to improved information processing and, consequently, a reduction in reading difficulties.
Keywords: Dyslexia, Working memory, Information processing speed, Persian language, Primary school children
Type of Study: Original Research Article |
Subject:
Psychology
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