Objectives The purpose of this paper is to identify dyslexia among various types of learning disabilities, explain its manifestation mechanism, and demonstrate it clinically.
 Methods This paper shows that through the fundamental cognitive mechanism, not only can the characteristics of dyslexia be understood in the most fundamental, essential, and holistic way, but also a better understanding of how dyslexia is fundamentally manifested. For clinical proof, non-verbal intelligence test (K-CTONI-2), Korean version of Children's Visual Perception Development Test (K-DTVP-3), the Korean Reading Test (KOLRA), and speech hearing test were administered to 7 elementary school students who continued to experience difficulties despite receiving reading education.
 Results Dyslexia begins with an excessively imbalanced structure of the brain's large visual and small auditory cognitive spaces. Due to the imbalance between the two cognitive spaces, visual acuity and visual memory appear strong, while auditory acuity and auditory memory appear weak, resulting in auditory internal attention deficit, which is the most important cognitive condition for language development. Auditory internal attention deficit in turn interferes with auditory information processing, resulting in serious difficulties in written language development and various symptoms observed in dyslexic children. The test results showed a low auditory function score compared to a high visual function score.
 Conclusions Dyslexia occurs due to functional defects in hierarchical cognitive processes such as auditory sensation, memory, and thought processing caused by an imbalance between the brain's small auditory cognitive space and large visual cognitive space. This paper presents directions for effective dyslexia treatment based on research results.