The cortex is split; it is in two halves, the right brain and the left brain. The disconcerting truth is that every one of us has not one but two brains. Even more disconcerting is the fact that these two brains are not just two halves of the same thing, or two replica brains or two mirror images of each other. Our two brains are quite separate individuals with different capacities and abilities – even different personalities. Your left and right brains have very different patterns of skills and see ‘reality’ from correspondingly different points of view. What one brain does well and easily the other may hardly be able to do at all. However, these two brains are joined together by a wide, thick band of millions of nerve fibres known as the corpus callosum. Your brains communicate so swiftly, so completely and so intimately, via this corpus callosum, that you experience them as a single brain. Each of your brains is kept so instantly and fully informed as to what is going on in the other that we cannot tell them apart – under normal conditions. However, very serious epilepsy was, at one time in the USA, treated by surgically cutting the corpus callosum, thereby suddenly isolating the brains from each other. The effect on the severity of the epilepsy was only sometimes improvement, but these ‘split brain’ patients were soon recognised as remarkable psychological subjects in which each brain might be accessed separately from the other, if the experimental or investigative method used were ingenious enough. Work with these patients has provided much of what we now know about our two different minds. (See also Springer and Deutsch 1997 and notes to this chapter.)
Somewhat simplistically, then, your left brain, your left cerebral hemisphere, is (almost always) the rather dry, logical, linear thinker. It is here that most nuts and bolts language management takes place, here that you mostly learn and deploy the skills of literacy. Your right brain (almost always) takes a more holistic view of the world, is more creative, perhaps, and a more lateral thinker. Your right brain is more ‘into’ the relationships between things than your left. Your right brain is probably better at hearing and enjoying the sounds of music or the beauties of art. It is as if you have two people in your skull neither of whom is a complete personality with a full complement of skills or characteristics. You can think of them as ‘Lee’ and ‘Roy’. Lee is a scientific thinker and articulate talker who is invariably logical and, at least on straightforward matters of fact, usually boringly correct. Roy, on the other hand, is unscientific but interesting; much ‘cooler’ than Lee. He digs his music, easily understands an engineering drawing and enjoys modern art, though he doesn’t talk much about any of this. These two different personalities, however, communicate so constantly and completely that they have fooled you into seeing them as a single person - ‘Leroy’ perhaps. Lee may be a boffin, or yuppie, and Roy may be an artist and hippie, but Leroy is a full and balanced personality as a result of their alliance.
The only reason for discussing our two brains at all in this context is that it was once widely thought that literacy acquisition was related to brain and hand dominance. People talked about ‘crossed laterality’ or ‘cerebral dominance’, and still occasionally do. This was because we had discovered that the hand of one side is controlled by the brain of the other. (Your left hand is controlled by your right brain and vice versa.) Not only that, there is dominance; one cerebral hemisphere, usually your left, dominates the other and one hand, usually the right, dominates the other. Most of us are right handed, so we actually write with the hand which is controlled by the left hemisphere, where literacy is mainly dealt with. A left hander, though, is writing with the hand which is under the control of the less literate brain, and the non-dominant brain to boot. It was thought that this must result in literacy difficulties – i.e. that left-handers would be more at risk of, say, dyslexia. None of this is regarded as true today. None of this, we now think, has anything whatsoever to do with literacy acquisition or performance, let alone dyslexia. Hemispheric dominance is irrelevant to our study, and so is handedness. I offer the discussion here merely as an item of historical interest and because you may come across references to crossed laterality or cerebral or hand dominance issues in odd or elderly corners of the literature. You may ignore these if you do.
We shall shortly be attributing different aspects of literacy and language learning and management to rather highly specified areas of the brain. This may be slightly simplistic, as I have already confessed, but if we keep our provisos in mind it will still amount to a reasonably true and practically useable account. In order to make sure that we really do bear this oversimplification in mind, and proceed sufficiently humbly, let us remember phrenology. A little over 100 years ago phrenologists claimed that there were different ‘organs’ within the brain and that these could be felt as a series of bumps on the skull. They claimed there were, for example, organs of cautiousness, destructiveness, constructiveness, acquisitiveness, congugality and (my favourite) mirthfulness. After comprehensively feeling all the bumps on your skull a phrenologist would attribute characteristics and abilities to the mental organs beneath the bumps, and claim to understand your particular personality from the size of your bumps. This was a charming theory, but wrong of course. Today we are more empirical and the phrenologist’s organs have been replaced by Brodmann’s areas (e.g. England and Wakeley 1991). We scan, observe and experiment and we claim (and hope) that our theories are based on rigorous and empirical, neurological evidence. For humility’s sake, though, I keep a facsimile phrenologist’s head right here on my desk. It keeps me sceptical, as is scientifically proper.