b-d Reversals: A Telltale Sign
of Dyslexia

The word "dyslexia" means "difficulty with words or language." A telltale sign of dyslexia is reversals. People with this kind of problem often confuse letters like b and d, either when reading or when writing, or they sometimes read (or write) words like "rat" for "tar," or "won" for "now."

A popular theory is that reversals are caused by a neurological deficit. In other words, there is something wrong inside the brain of the person. While many factors can contribute to dyslexia, one should not overlook the principle that perception of anything depends on our past experiences.

Before one can read or learn anything, one has to become aware of it through one of the senses. Usually one has to hear or see it. In other words, perception must take place. Subsequently one has to interpret whatever one has seen or heard. In essence then, perception means interpretation. Of course, lack of experience may cause a person to misinterpret what he has seen or heard. In other words, perception represents our apprehension of a present situation in terms of our past experiences, or, as stated by the philosopher Immanuel Kant (1724-1804): "We see things not as they are but as we are."

The following situation will illustrate how perception correlates with previous experience:

Suppose a person parked his car and walked away from it while continuing to look back at it. As he went further and further away from his car, it would appear to him as if his car was gradually getting smaller and smaller. In such a situation none of us, however, would gasp in horror and cry out, "My car is shrinking!" Although the sensory perception is that the car is shrinking rapidly, we do not interpret that the car is changing size. Through past experiences we have learned that objects do not grow or shrink as we walk toward or away from them. We have learned that their actual size remains constant, despite the illusion. Even when one is five blocks away from one's car and it seems no larger than one's fingernail, one would interpret it as that it is still one's car and that it hasn't actually changed size. This learned perception is known as size constancy.

Pygmies, however, who live deep in the rain forests of tropical Africa, are not often exposed to wide vistas and distant horizons, and therefore do not have sufficient opportunities to learn size constancy. One Pygmy, removed from his usual environment, was convinced he was seeing a swarm of insects when he was actually looking at a herd of buffalo at a great distance. When driven toward the animals he was frightened to see the insects "grow" into buffalo and was sure that some form of witchcraft had been at work.

To summarize, in order to be able to interpret size constancy, one must have had enough exposure to wide vistas and distant horizons. In the same way, in order to be able to interpret position in space — the learned perception that makes it possible to distinguish a b from a d — one must have had enough exposure to relevant experiences. Relevant experiences include the ability to distinguish left and right and the ability to cross the midline.

The human body consists of two halves, a left side and a right side. The human brain also has two halves, which are connected by the corpus callosum. Mindful of the wise words of Immanuel Kant that man does not see things as they are but as he is, it is inevitable that a person will interpret everything in terms of his own sidedness. A child or adult, who has not learned to interpret correctly in terms of his sidedness yet, who has not learned to distinguish properly between left and right, will inevitably experience problems when he finds himself in a situation where he is expected to interpret sidedness. One such a situation, where sidedness plays a particularly important role, is when a person is expected to distinguish between a b and a d. It is clear that the only difference between the two letters is the position of the straight line — it is either left or right.

It is important to note that people who are confused about left and right cannot use mnemonics or memory aids while reading, as is often advised by experts. Susan Hampshire, for example, advises that children should remember that "left" is the side on which they wear their watch. This never works to improve reading ability. It can be compared to learning a language. One cannot speak a foreign language if one only has a dictionary in that language. One has to learn to speak it. In the same way one has to learn to interpret sidedness. As all the other skills foundational to reading, the ability to distinguish between left and right must be drummed in so securely that the person can apply it during reading (or writing) without having to think of it at all.

The role that memory plays in any learning situation should of course not be overlooked. A child (or adult) with a poor memory might be unable to learn the relevant experiences.