Visual and Auditory Processing Deficits in Developmental Dyslexia: A CHC-Theoretical Perspective

Dyslexia is a specific learning disability of neurobiological origin, characterized by persistent difficulties in accurate and fluent word recognition, spelling, and decoding. This paper explores the cognitive foundations of dyslexia through the Cattell-Horn-Carroll (CHC) theory of cognitive abilities, focusing on Visual Processing (Gv) and Auditory Processing (Ga). Weaknesses in Gv, e.g., deficits in visualization, spatial scanning, visual memory, and closure speed, are linked to letter reversals, poor orthographic mapping, and slow word recognition. These difficulties may stem from disruptions in the visual neural system (VNS), including the magnocellular, parvocellular, and koniocellular pathways. In particular, magnocellular dysfunction affects motion detection and visual timing, impeding fluent reading. Similarly, weaknesses in Ga, including phonetic coding, sound discrimination, and auditory memory, contribute to phonological deficits, decoding issues, and spelling challenges. Together, these impairments hinder the integration of orthographic and phonological systems, essential for reading fluency. Beyond cognitive factors, the paper considers the emotional impact of dyslexia, noting how repeated academic struggles can lead to anxiety, low self-esteem, and depression. Applying CHC theory enables more targeted, strengths-based interventions that support both academic growth and mental wellness. This integrative approach underscores the value of CHC theory in fostering cognitive insight and holistic support for students with dyslexia.