Contributing Factors of Dyslexia

What Factors Contribute To Dyslexia?
See also: Definitions of Dyslexia | Dyslexia Diagnosis | To Teach a Dyslexic

Ocular | Language | Visuo-Spatial-Motor | Other Factors

Ocular Problems

Several reliable studies (Helveston 1969; Blika 1982; Keys 1982; Hiatt 1984) have found that dyslexic individuals have no greater incidence of eye problems than do individuals with normal reading ability. Such parameters as visual acuity, stereo acuity, ocular alignment and motility, fusion status (break point amplitude), and refractive error have not been shown to be significantly different in poor versus normal readers. Individuals with reading problems should, however, have a careful eye examination as part of an overall medical examination. There is no scientific evidence that visual training (including eye muscle exercises, ocular tracking or pursuit exercises, or glasses with bifocals or prisms) leads to significant improvement in the performance of dyslexic individuals.

Translated into plain English, this means a dyslexic should have his eyes checked, but improved vision doesn't help that much in learning to read.

Language Problems

According to Mattis (1978), the primary contributing factor to dyslexia is an auditory language deficit. Approximately 86% of the individuals identified as dyslexic evidence an auditory language disorder that prevents the individual from linking the spoken form of a word with its written equivalent. In light of this, any individual with reading problems should have a careful evaluation of his or her language capabilities and where indicated, appropriate speech and language intervention should be provided.

Translated into plain English, this means the brain of a dyslexic has problems translating speech to written language.

Visuo-Spatial-Motor Problems

In contrast to language problems, visuo-spatial-motor factors of dyslexia appear less frequently (Robinson and Schwartz 1973). Approximately 5% of the individuals identified as dyslexic have a visuo-spatial-motor problem that interferes with sequential organization, scanning, and the perception of temporal and spatial cues. Although visuo-spatial-motor confusion is common in young children who are just learning to read, these problems do not tend to account for severe and persistent reading difficulties unless the child has missed so much basic reading instruction that he cannot get caught up. Assessment of visual, spatial, and motor capacities should be included in the diagnosis of any coordination or orientation disorder; however, there is no scientific evidence that interventions such as neurological and sensory organizational training, laterality training, dominance training, balance beam, or reflex inhibition will significantly accelerate reading performance.

Translated into plain English, this means that a small number of dyslexics have problems visualizing things, problems with hand-eye coordination, muscle control, and sense of time and space. This should be assessed but treatment of any of these problems won't be of much help.

Other Factors

The importance of general intelligence in learning to read has been examined and shown to be a critical factor in both reading and language abilities. Investigations of the role of dominance in handedness, eyedness, and mixed laterality have produced no consistent conclusions. Studies investigating low birth weight, EEG abnormalities, temperamental attributes, attention deficit disorders, birth order, food additives, and chemical allergies have yielded mixed results. What is clear is that a wide range of factors can be associated with reading difficulties but that these factors work differently in different children.

Translated into plain English, this means that the experts don't really know or agree about what causes dyslexia or how to treat it. No one elegant explanation of cause has yet been found.