Typical, non-dyslexic readers rely on a brain system that begins with perception of the letter sequence or words via the visual cortex in the posterior region of the brain (Visual Word Form Area or VWFA), and continues in the auditory cortex in the left temporal (midbrain) region, where sounds of speech are ordinarily processed (Wernicke's area). For more complex reading tasks, the left frontal regions involved in logical thought and speech production (Broca's Area) are also invoked.

In contrast, dyslexic readers who become capable readers do most of the work of reading in their frontal lobes, relying on a more extensive use of left frontal systems, including Broca's Area, and on corresponding right brain systems. Visual cortex activity is substantially reduced, as dyslexics do not invoke the VWFA system, and the Wernicke's area is bypassed. In other words, the evidence shows that the non-dyslexic reader's brain moves from sight to sound, quickly transferring the visually perception of the word to the parts of the brain invoked in listening to words.

This system is not effective for dyslexic readers; brain scans show that those dyslexics who follow this mental route for reading remain persistently poor readers through adulthood. For the dyslexic who acquires good literacy skills, the brain does not process the word in the visual cortex, but rather uses the speech production areas of the brain in combination with analytical thought systems. The left-brain systems are associated with logical though and analysis, whereas the right-brain systems are associated with resolving ambiguities and intuitive thought. So for the literate dyslexic, reading is a process of moving from visual perception to conceptual thought.

Science also shows that the dyslexic brain can be trained to rely more on the auditory areas used by non-dyslexics, and that even with very short-term intervention, such changes can be seen in brain scans as well as improved ability to relate words to their component sounds.

However, this does not translate to improved reading fluency or comprehension skills. Rather, dyslexic children who have been trained in such skills show evidence of reduced comprehension skills. Dyslexic adults whose brains reflect a visual-to-auditory pattern tend to be persistently poor readers.

The reasons for this disparate pattern may be due to physical brain structure; there is some evidence that the Wernicke's area in the dyslexic brain is physically smaller, while right-brain areas may be larger, when compared to the brain of a non-dyslexic individual. It may also be developmental, perhaps influenced by genetic factors which govern the rate and pattern of brain growth and development, as well as environmental factors. Possibly it is also influenced by hormones, as studies indicate that about half of non-dyslexic women also rely on the right-brain frontal areas used by dyslexics for some reading tasks, and that estrogen levels influence the pattern of brain use.

Thus the evidence shows that, not only does the dyslexic brain function differently, but that it must function differently if the dyslexic is to acquire good literacy skills. Actually, there is both a disadvantage and an advantage to the functional difference in the dyslexic brain. The disadvantage as that the system used by non-dyslexics is quicker and more automatic, and also can be acquired at an earlier age; most non-dyslexic children can learn to read well at about age 6, when their mid-brain system for listening to and understanding language is already well-developed.

In contrast, the dyslexic brain system is primarily reliant on frontal areas related to analytic thought processes that develop later in a child's life, and dyslexics who become capable readers and writers often do not acquire literacy until around the ages of 10-12, when their brain development has reached what Piaget called the stage of formal operations. The advantage for the dyslexic reader lies in the fact that, in relying more on intellect than on listening skills, the dyslexic has built a foundation for a deeper understanding of what is read and stronger abilities to analyse complex ideas and resolve ambiguities. Thus, while the dyslexic reading system is inefficient for the simple concepts typically presented in primary level readers and day-to-day reading tasks, it is primed for the complexity encountered as reading demands increase at the high school and college level. For this reason, dyslexics often follow the pattern of being "late bloomers" who struggle during early years, but often excel and are far better than their peers at integrating new knowledge at the high school and college level.

Unfortunately, because of misconceptions about reading and dyslexia, our educational system is geared primarily toward trying to teach dyslexic children to learn to read by exercising the subsidiary reading skills used by their non-dyslexic counterparts. Emphasis is placed on developing phonemic awareness and practicing reading through phonics, and on drill and repetition to memorize basic sight words. These strategies not only fail to help the dyslexic learner, but in the long run they may undermine the process of development of the frontal brain regions so desperately needed for reading, both because they reinforce neural pathways that are ineffective for the dyslexic reader, and often children receiving such instruction are simultaneously denied exposure to the enriched educational environment that would promote advanced intellectual development.

This dyslexic difference can be explained by the model of picture-thinking vs. word-thinking. That is, the dyslexic thinks mostly with visual imagery, whereas the typical, non-dyslexic learner thinks mostly with the sounds of words. Brain scan research does also show that individuals tend to prefer either primary language-based problem solving approaches or visualization-based approaches; that these are reflected in different brain use patterns; and that individuals tend to reinforce their favoured modality through their thinking and learning processes, building stronger neural pathways and gaining proficiency.

Because these differences appear to be persistent through life and tied to neurological causes, educators must recognize that dyslexic children will learn to read through different strategies and follow a different timetable for acquisition of strong literacy skills than non-dyslexic learners.

Standardized assessment tests of basic early reading skills may validly be used to develop a learning profile and direct students to appropriate educational resources, but they must not be used as barriers to prevent advancement in school, as such barriers deny children access to the age- appropriate and enriched classroom content and activities needed to stimulate growth in the brain regions that will ultimately be essential for acquiring advanced literacy skills.

Further, when children are struggling to learn to read, the focus of teaching should not be primarily on remediating weaknesses in basic skills, but on developing the intellectual skills that will ultimately provide the basis for advanced reading comprehension skills. Instruction in areas of weakness may be provided, but it should not be done in an intensive, systemized fashion, but rather offered in an integrated fashion with other instruction, so that the child learns naturally, in accordance with his or her own distinct learning style.