Developmental Dyslexia is dyslexia that is not caused by brain trauma. It is a language-based learning disorder. It is neurological in origin and characterized by poor spelling and decoding abilities. Basically, Developmental Dyslexia affects the ability to learn to read and spell, and sometimes math is affected as well. It is usually not related to general intelligence. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities, and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and background knowledge. It is important to note that few individuals exhibit all signs of dyslexia. Difficulties with sound and language processing are the underlying deficits for individuals with dyslexia. Children with dyslexia find it hard to remember lists of things they heard earlier, or find it difficult to remember names or facts quickly. However, they often have strengths in reasoning, as well as in visual and creative fields (International Dyslexia Association, 2002, ASHA, 2001). The child with dyslexia will struggle with reading printed sentences/paragraphs, writing with a pencil, spelling accurately from memory, and developing sentences/paragraphs with correct grammar and punctuation.
Dyslexia may also include conveying information orally and listening to oral information. Although the child with dyslexia tries and tries, certain errors continue with reading, writing, and spelling. Most children with dyslexia also have Auditory Dyslexia or difficulty processing the basic sounds of language (phonemes), sounds of letters, and groups of letters, resulting in very slow and labored reading. Although sounds are captured by the ears without difficulty, the brain processes the input less accurately. Dyslexia and writing difficulties often co-occur. First of all, reading and writing rely on related underlying processes. Dyslexia involves difficulties related to processing phonological information needed for decoding words, whereas writing requires encoding phonological information when writing words. Since dyslexia impacts the underlying process for both the reading and writing systems, the prevalence of writing difficulties for students with dyslexia is not unexpected. Also, reading is a sub-skill required throughout the writing process. Writers often need to read source materials before writing their own text and also need to read and reread their own writing to diagnose text problems, such as spelling errors, grammar errors, and disorganization. The presence of reading difficulties complicates this task, especially if a student has poor handwriting skills that make it even more difficult for them to read their own writing (Graham & Herbert, 2010, 2011). Poor handwriting may be due to poor spelling skills versus just poor handwriting skills.
Regarding the topic of Visual Dyslexia, it has little to do with the eyes, except scotopic sensitivity (word blindness) or irregular eye movements. Incomplete neuronal development within the visual cortex makes it impossible for this portion of the left brain to recognize printed symbols correctly. This is where print reverses, scrambles out of sequence, or is perceived upside down. Many children have strong emotional reactions to content of what they see in pictures or on the printed page. The visual cortex fails to interpret symbols from left to right and top to bottom.
Dyslexia may be overcome or reduced, but it cannot be eliminated. Most children with dyslexia can learn to compensate for it successfully with treatment (International Dyslexia Association, 2002).