Dyslexia & Phonological Deficiencies

It has been posited that all or most dyslexia is initiated by phonological deficiencies in the brain, and some have further drawn the conclusion that all remediations must be phonologically based.

If someone has a phonological deficiency, this is not a good rationale for further imposing colorblindness.

The brain uses a wide variety of measurements to form memory clusters and organize them. Any deficiency creates errors which cascade to the remaining measurements. Every problem we describe as stemming from a deficiency to utilize color could likewise be observed for deficiencies when processing sound. There is no reason to compound them. There is no easy fix for a deficient phonological system, whereas the color system is completely untapped.

Our internal surveys have shown that approximately 30% of dyslexics report phonological problems. Much has been made of a 2018 study which implied that most or all of dyslexia was phonologically based. The methodology of this study asked students to read aloud, requiring them to engage visual and phonological systems simultaneously. The vast majority of reading is done silently, which is very different from the conditions studied.

Symptoms reported by dyslexics can not be completely accounted for by phonological confusion. Optical illusions demonstrate clearly that even without any audio component, visual perception can result in images that flicker, floating, or rotate. Confusion centered on shapes like bdpq, and eyes tracking to the wrong line all demonstrate that visual problems can exist independent of phonological problems.

In October 2025 the International Dyslexia Association unveiled the result of a 2 year project to modify their 2002 definition of dyslexia. This project included input from thousands of research professionals and educators around the world and resulted in a modification of their previous stance which emphasized phonological components as the root cause of dyslexia.

Their 2002 definition stated in part:

“difficulties typically result from a deficit in the phonological component of language”.

In 2025, this clause was replaced and now reads:

“The causes of dyslexia are complex and involve combinations of genetic, neurobiological, and environmental influences that interact throughout development. Underlying difficulties with phonological and morphological processing are common but not universal, and early oral language weaknesses often foreshadow literacy challenges”.

At the unveiling of the new definition, multiple speakers who were involved in the redefinition stressed the need to expand beyond a phonological-centric and certainly a phonological-only understanding of the causes of dyslexia. As one speaker put it, “We know from research that it’s not deterministic and it’s not always present.”

A primary goal of ongoing RexLex testing is to demonstrate that silent reading can be improved independent of phonological remediation.