Phonological deficit hypothesis

The phonological deficit hypothesis is a prevalent cognitive-level explanation for the cause of reading difficulties and dyslexia. The hypothesis is based on evidence that individuals with dyslexia tend to do poorly on tests which measure their ability to decode nonsense words using conventional phonetic rules, and that there is a high correlation between difficulties in connecting the sounds of language to letters (phonemic awareness) and reading delays or failure in children.

Source: Wikipedia — Phonological deficit hypothesis (CC BY-SA 4.0)