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The Dyslexia Hypothesis

January 19, 2009

Another excellent essay/guest post by Unity, for which, thanks. Originally posted today at Ministry of Truth. This post is part of the Is Dyslexia A DisAbility? debate at Same Difference.


To pick up the full background to this post, you’ll need to read this article of mine at Lib Con, and this response from Letters From A Tory, first…

Finished? Good, then we’ll move on.

There’s an common exercise that was widely used by English teachers back when I was at school, one which may well still be in widespread use.

In this exercise, you’re asked to imagine that your writing to a pen pal from a foreign culture, or maybe an alien; someone who, where ever you may have been told they we’re from, is completely unfamiliar with the society and culture in which you were born and lived your life. Next, you’re given or asked to think of a very mundane and routine task that people in your own society undertaken on a daily basis, something like making a cup of tea or tying your shoelaces, and what you have to do to complete the exercise is simply write a set of instructions explaining to your pen pal exactly how to carry out that task, instructions that they could then follow in order to perform the same task themselves, even though its something they’ve never, ever, done before.

That all sounds really simple, doesn’t it? And it is, until you try to do it.

Personally, I always liked the ’shoelaces’ version of this exercise, because it lends itself really well to a simple demonstration of just how difficult an exercise this really is. You can easily give a completed set of instructions written by one student to a different student and ask them to tie their shoelaces by following the instructions they’ve been given to the letter, with entirely predictable and often very amusing results, i.e. a complete and utter mess which nothing whatsoever like the neatly tied shoelace that the first student was trying to describe.

Aside from being a nice little exercise in structured writing, that exercise is intended to make a very important point about us and how we relate to the world we live in, a world in which we routinely carry out any number of complicated and hard-to-explain tasks, tasks we complete seemingly without much conscious effort and without ever considered just how complicated they really are.

Now, lets think about a task, and a skill, that most of us take entirely for granted.


You’re doing it right now and I’m willing to bet that most of you have never given a moment’s thought to just how complicated an task you’re undertaking, and doing, without any real conscious effort.

Now try thinking abvout reading in terms of the ’shoelaces’ exercise.

To try and keep it simple, think about reading in terms of ’systems’ for the moment, discrete processes that your brain has to carry out in order for you to be able to read. Taking it as read that the eye takes in information about the world and what you see in front of you (even though that a complicated task in itself when you think in terms of everything the brain needs to coordinate in to focus on and scan the text you’re reading with your eye) you’ve then got to take the information that the eye sends to your brain (a picture), process it to extract the information you need (the symbols that make up letters and words) from all the other information in the picture, figure out which of those symbols are meaningful (i.e. one you can recognise as letters/words rather than meaningless marks and squiggles).

Once you’ve got some meaningful symbols to work with, you then have to decode them to find out kind of information those symbols convey and whether that any of that is meaningful, which means both figuring out which arrangements of symbols actually make recognisable words rather than unintelligible strings of random letters and whether the words in an order/sequence which make grammatical sense, converting all this information into a form that the brain recognises as language – and there are some very good reasons why we believe that, in order to do that task, the brain converts the visual information it receives into an internal representation of spoken language – at which point we can apply meaning to that information and actually understand what it says.

Most of us manage all that so rapidly and effortlessly that we wander through life without ever really thinking about just how complicated the process of reading is, in fact we’re barely even aware that it takes any real effort at all, unless we run into a word (or words) that we don’t understand in terms of their meaning and even then, as long as the word is written in the symbols we’re familar with as representing our own language, what we call the Latin alphabet, and the word is structured in terms of its arrangement of vowels and consonents, in accordance with the ordering rules of our own language, we can still ‘read’ the words; we can get as far as converting the symbols into an internal representation of the sounds of language (phonemes) and, give or take a bit of dodgy pronunciation, speaks the words, for all that we might have no idea what they actually mean. To really stump a native English speaker, you have to confront them with a language, such as Chinese, which uses a completely different set of symbols.

What I’m trying to explain here is simply that, for that reading may seem to be something we do almost effortless, as a neurological process its an extremely complex task and, as with any task, the more complex it is the more scope there is for something to go wrong somewhere in the process. Moreover errors occurring at different stages in the process will create very different types of flaws in what we can see here in world outside the brain; different errors occurring at different stages inthe process of reading will produce different ’symptoms’ and also, because we’re dealing a process and not a single task, errors in one stage of the process may easily give rise to even more errors later in the process, amplifying the effects of the original error. (We also know the brain has some pretty nifty error correction mechanisms its uses when we we read, otherwise we’d get stuck every time we ran across a simple typo – but that’s a story for a different time).

So, when LFAT complains that:

At best, dyslexia merely refers to a cluster of symptoms that the vast majority of, if not all poor readers demonstrate – speech problems, writing problems, slow processing etc.  The astonishing thing is that the BDA websites then goes on to list “possible difficulties” that those with dyslexia might show: “reading hesitantly, misreading (making understanding difficult), difficulty with sequences (e.g. getting dates in order), poor organisation or time management, difficulty organising thoughts clearly, erratic spelling.”

The neuroscientists’ immediately response will be, ‘Yes, but what of it. This is an extremely complex system we’re dealing with’.

LFAT would have you believe that, because its impossible (at present) to pin down dyslexia to a clearly defined pathology and set of symptoms, that supports the contention that it doesn’t exist. In reality, that ‘evidence’ merely supports the view that what we dealing with are problems affecting the development of an extremely complex system, one in which there are many different things which could go wrong.

In short, what makes dyslexia a specific condition, as distinct from other types of ‘reading difficulties’ is that its cause lies in the existence of flaws in the complex, underlying, neurological mechanism which enables to read.

This observation leads us to several difficult but inter-related questions, to one of the most intractable philosophical disputes in psychology, nature vs nurture, and a recent discovery that may go a long way towards settling that dispute and, also, to a political debate that succeeds in being both very contemporary and as old as the hills at the same time.

The main bone of contention is all this is, based on our current knowledge of dyslexia and the various diagnostic methods we have to hand, its extremely difficult to draw a clear dividing line between dyslexia and other ‘conditions’ that also result in the delayed acquisition of reading skills.

So, what kind of other ‘conditions’ are we talking about here? Well, certainly not the organic variety, the one’s that are caused by brain injuries, lesion and tumours or which form part of an obvious learning disability of the kind that adversely affect not only an individuals ability to read (and write) but their intelligence and their ability to function independently in the absence of a significant degree of external care and support. Most of those are very easily picked out from either a CAT or MRI scan or using a battery of intelligence and developmental tests in which the subject will, almost always, be found to exhibit uniformly low scores across all significant measures of intelligence and ability. No, what seems to bother many of the ‘dyslexia deniers’ is the existing diagnostic regimes apparent inability to reliably sift the sheep from the goats, the deserving from the undeserving, the kids who might genuinely have a neurological condition that inhibits or limits their capacity to acquire reading skills from those whose ‘condition’ can be traced back to their living and growing up in a home environment in which the only reading material on offer may be this week’s TV guide.

At various times this creates a degree of political antipathy towards the process by which dyslexia is commonly diagnosed.

Some on the left have a major problem with the fact that an individual’s home environment has, certainly in past, had a significant influence on whether a particular individual is diagnosed as having dyslexia or simply labelled as being ‘think’, ’slow’ or ‘educationally subnormal’ on the assumption that when a child has a stockbroker for a father, a teacher for a mother, and grows up in home environment that would put a small branch library to shame then any difficulties they have in reading must, obviously, be caused by something outside their control; while a child whose father is a labourer and mother a pub cleaner will automatically be thick, lazy or otherwise a product of, and failed by, their poor upbringing, regardless of whether dyslexia might actually be the underlying cause not only of their own problems but those of their parents.

So, some on the left contend, the diagnosis of dyslexia is prone to, and even riddled with, class-related biases and prejudice.

As for the right… well, LFAT provides a neat summary of the issues that most seem to tax ‘dyslexia-deniers’ on that side of the political divide:

The fact that, once diagnosed, children with dyslexia can get laptops, extra time in exams, extra help from teachers and all the rest of the package is an outrageous waste of taxpayers money and should be rechannelled into helping everyone learn to read properly in the first place.

See, not only are the kids who’re diagnosed with dyslexia being handed an unfair advantage by being given extra time in exams and additional teaching support by the bastards are paying for all this with my taxes as well, money that I could be spending on buying advantages for my own precious offspring if only the government weren’t stealing it out of my salary to give to the thickos…

That’s almost certainly (hopefully) an exaggeration of LFAT’s views, but its one, nevertheless, that’s creeping into the public debate surrounding dyslexia because its fits neatly with some people’s political beliefs about society, merit. privilege and the nature of the relationship between the individual, the family, society and the state. I doubt that I need elaborate any further on that point – you’re reading this on a blog and if you read blogs, generally, then you’ll know perfectly well what kind of attitudes and beliefs I’m referring to here.

None of that, of course, settles the question of whether dyslexia is a genuine neurological condition, but it does provide some useful additional context to the current debate and the motives of at least some of the participants in the wider debate, and this goes some considerable way to explaining the apparent popularity of Julian Elliott’s ideas in some quarters. It has to conceded that, in part, he makes a fair case in favour of the proposition that dyslexia may be over-diagnosed and used, by some as much as a palliative to quells the fears of some over-anxious parents but for all the superficial plausibility of his claim that dyslexia doesn’t exist there’s a gaping whole in his hypothesis which he fails to address.

Even if we allow the possibility that a child’s family background, home environment and other related environmental factors may account, more accurate, for some unspecified proportion of the current incidence of diagnosed dyslexia it remains a fact that there some children who learing to read an immense struggle even though they come from the kind of background which you expect should provide them with all the possible environmental advantages they could wish for and more. These kids come from good homes, have no family history of development delays of any kind, score very well on the battery of cognitive and other test used to assess their intelligence and intellectual capabilities and, on verbal and spatial tasks, perform as well if not better than they classmates. Some have even attended independent schools where the teaching of reading using synthetic phonics has remained the norm throughout, which rather knocks a hole in the claim that this alone is a universal panacea for ‘reading difficulties’ – and while we’ve got that one on the table its worth pointing out that there was rather more to the West Dunbartonshire experiment than just synthetic phonics…

Synthetic phonics, where children learn to sound out the single and combined sounds of letters, has been at the core of the scheme but it has not been the only factor. A 10-strand intervention was set up, featuring a team of specially trained teachers, focused assessment, extra time for reading in the curriculum, home support for parents and carers, and the fostering of a “literacy environment” in the community.

Anyone like to guess how much taxpayers money that little package of educational extras might have swallowed up?

Oh, and without wishing to sound like I’m nitpicking… errr, okay, so I am nitpicking…

… none of the research papers or reports on the West Dunbartonshire initiative appear to have been published in peer-reviewed journals and to get any of them, even in an electronic format, you have to e-mail the local authority and ask for a copy. Not even Strathclyde University, which is where the educational psychologist behind the West Dunbartonshire initiative, Tommy McKay, is a visiting professor, appear to have copies of any of the research available for download. So, while I hate to have to be the one to point this out, but given what we now know about the increasingly notorious Durham Fish Oil Study and its serious methodological shortcomings, I’d personally hold off on getting too enthusiastic about West Dunbartonshire until we see a few signs of the study being subjected to peer review and independent evaluation.

The lack of any evident peer review or independent evaluation of this initiative is a little troubling, given the claims made for the programmes efficacy, and it doesn’t help matters that some of the reported figures relating to this project don’t seem to add up.

One such figure, which made it into several newspapers, claims that around 50,000 children were assessed during the 10 year life of the programme which, if true, would indicate that the offical population figures for the number of children living in the area out by about 100%. Based on the official stats, in any given year the school/nursery age population of the area will be around 14,000 children and this, when you allow for the numbers of children entering and leaving the system each year over a ten year period gives an estimated total school population for life of the programme of about 25,000 – so while I can buy the idea that programme carried out 50,000 assessments by getting round the school population twice, there’s no way that 50,000 children were assessed because there were only around half that to assess in the first place.

Fair enough, that’s almost certainly going to be no more than a bad case of scientific illiteracy somewhere between the Council’s Press Office and the newspapers in which those figures appeared but in the absence of any peer reviewed write-ups to work with those kinds of overstatements will tend to place question marks, maybe unfairly, against the programme and make you wonder whether or not it really is its been cracked up to be.

We’re drifted away from the central question of whether or not dyslexia exists but for godd reasons, because what I hope you’ll have picked up here is the evidence being put forward in support of the contention that dyslexia doesn’t exist is a long way from being conclusive and that there’s a hell of lot more to teaching kids to read than a few arguments over the right choice of phonics system to use in schools.

Okay, let’s hit the homestretch by doing something that’s markedly absent from Julian Elliott’s opinions of dyslexia and LFAT’s arguments – some real science.

We should be clear at the outset that what I’m not going to do here is definitively prove that dyslexia exists – sorry but I don’t have the time, research grants, extensive pool of test subjects and high resolution MRI scanner I’d need to pull that one off.

No, what I’m going to do here is try something extremely radical by putting together a single hypothesis for dyslexia that will demonstrate that there is a neurological mechanism that underpins the condition, that accounts for the available evidence and, as a final party piece, also unifies the list of theories and hypotheses that have been proposed to explain dyslexia (which you can get quick overview of in this wikipedia article under the heading ‘scientific research‘). In the process you’re also going to get a crash course in evolutionary neuroscience, unlearn a couple of common myths about the nature of the human brain and discover that it does some very surprising things that, until recently, no one suspected that it was capable of, explain why synthetic phonics is pretty much the best approach we can take when it comes to teaching kids to read and blow a hole in the entire nature vs nurture debate big enough to seriously annoy everyone from Marxists to Educational Psychologists…

…and I may even throw in a gag or two in along the way.

Let’s start at the philosophical end of thing by tackling the roots great nature vs nurture dispute and explaining why dismissing genetics as a factor in dyslexia is not just a mistake but a sign of a near total failure to understand the the neurological processesand mechanisms that underpin not only learning but everything that makes us human beings.

Unless you’re got some serious wild religious notions about ‘god’ individually fashioning every single living thig on the planet then you should be fairly comfortable with the whole business of heredity and the idea that, through out genes, we inherit certain characteristic from our parents and, sometimes, even more distant ancestors. If you’ve got kids yourself, then you’ll know that just about the first thing most of you family and friends did on encountering your offspring for the first time was start speculating about which bits of the poor little mite’s appearance might of come from which parent or grandparent and who in the family the kids most resembles. Personally, I’m not the biggest fan of this kind of thing but then that’s because, when it comes to newborn babies, which is the time you have to put thing kind of thing the most, I reckon they all look like Winston Churchill.

That’s besides the point, which is simply that, at a basic level, the vast majority of people ‘get’ the idea of genetics and heredity and are entirely comfortable with the idea that at least some of our physical characteristics and traits. However, mention behavioural genetics, the suggestion that we may just have evolved certain heritable traits that might influence the way we behaviour, our personality and how perceive and interact with the world and other humans, of course, and its then that the objections come flying in.

Some people, particularly Marxists and ‘radical feminists’, really dislike the idea of behavioural genetics because it doesn’t fit very well with their ideological view that see human society and, by extension, humans as being almost infinately malleable in the face of external cultural and political influences, largely because  and whole idea of behavioural genetics suggests (to them) that some the characteristics they’d really like to change might be somehow fixed and immutable. Many other people think (wrongly) that the whole notion of behavioural genetics is somehow incompatible with concepts like free will and moral agency. and some people either believe that mind is somehow a separate thing or harbour religious notions about us possessing a soul, which leads them to believe that there’s no way that our genetic inheritence can influence the way we think and behave.

What all these people have in common, apart from their dislike of behavioural genetics, is that they really don’t understand what behavioural genetics is or what it tells us about… well, about us.

A quick word of warning here, if you’re the kind of person who thinks that the world and everything in it was created by god, especially in six days, then you may want to skip the next bit because we’re going to talk about evolution.

For everyone else, we’ll just take it as read that you’ve got the general gist of how evolution works in terms of accumulated changes over long periods resulting from random mutation and natural selection and barrel straight on to what evolutionary neuroscientists have been figuring out, fairly recently, about the realtionship be evolution, genetics and human behaviour, which goes a bit like this.

Making sense of the world around us, even at the most basic level of processing all the sensory information we have to deal with every second of the day is an extremely intensive task because there’s just so much information the brain needs to process – and if we don’t process that information very well and, at least, figure out which bits of information are much more important than others then the consequences can be pretty dire. Back in the days before civilisation – yes, cavemen always get a mention when you’re talking about evolutionary neuroscience, that’s just the rules – your distant ancestors might well have found the sight of butterfly utterly captivating, but if getting caught up in the beauty of the natural world meant not noticing the lion lurking in the long grass then your life expectancy was going to end up being much shorter than your attention span.

In all that, thinking your way through the world in a concious way, the way we assume we deal with the world around us, turns out to be not only an intensive task for the brain to undertake but also a relatively slow one, by the time you’ve taken a close look at the big tan object hurtling towards you, figured out that its a) a lion, b) hungry and c) heading directly for you… well, you should be able to figure out the rest.

So, over millions of years, the brain has evolved a number of ways of cheating and cutting down on the heavy overheads associated with thinking and conscious thought, developing hardwired systems that handle much of the basic information processing we have to do to make our way in the world without our even being aware that the brain is doing it. So, somewhere in the brain there’s a bit of internal circuitry whose job is simply to scan the constant stream of visual information the the brain gets from the eyes looking for lion-shaped objects and if spots something that looks like its fits the bill is starts sending out warning that trigger off various responses in other areas of the brain; the fight or flight reflex starts to kick in and pump adrenaline into the system in case we need to run for it, the areas which process our emotions get a message telling it that we really should be feeling a bit nervous and uneasy and, last of all in terms of speed,  the cumulative effect of all these other messages bleeds through into our conscious thought processes and we get the feeling the we really should be looking around to see just exactly what it is that’s making us feel so uneasy.

It turns out that what evolutionary neuroscientists are beginning to uncover is the fact the human brain has lots of the ‘black box’ processing systems – we call them black boxes because although we know information goes in and responses come out of them, quite what they do in between and how they process the information we don’t know, in fact we’re not even consciously aware that these systems are doing what they doing, they just do it anyway and we respond to their output, which we often refer to ‘gut instinct’ or ‘just having a feeling’, which is about all we can consciously make of the information they kick out.

Now, here’s the part that will really bake your noodle because alongside the obvious and, frankly, uncontroversial black box systems that we already uncovered, the ones that, for example, pick out recognisable object, symbols and patterns for visual information, there are other system which process information for us in some very surprising and unexpected areas… like when we’re making moral judgements and choices.

No, seriously, research has found that we have a system which, without our even being aware of it, processes basic information about situations in which we face moral choices and judgement and which tries to make some very basic decisions for us. It categorises the situation for us in terms of whether the choice we need to make, and the actions that follow, would be morally obligatory, permissible or forbidden and, having made its decision, it triggers the relevant emotional reponse to the situation, a response that ew then consciously attempt to rationalise in terms of the conscious thoughts and beliefs about morality. This system doesn’t exert absolute control over our moral choices, once we start trying to rationalise hoe we fell about the situation we also have the option of overriding the internal message in favour a choice that we’ve conciously reasoned out, but that system is there, nonetheless, prodding and prompting away in response to the information is receives from the outside world.

Now you’re probably wondering just how it does all that, or more to the point, how does this system know what kind of moral values we have, given that we’re not concious of what its doing and it appears to operate independently of our conscious thought processes. That’s a very good question, and one I’ll come to in a moment but before we get to that, its worth noting that a number of these black processing systems play a significant role in processing language, both from auditory input (the spoken word) and visual input (reading) and some of the processing that gets done automatically is what we’d consider pretty high level stuff, sorting out correctly formed words from meaningless noises or jumbles of letters and even processing language input for it grammatical structures – and if you know your linguistics, then yes, that is a neurological model (and partial validation) of Chomsky’s theories about universal grammar.

So, getting back to the morality black box, how does it know what our moral values are? Well, the answers obvious, it learns from the environmental input it receives from the society, culture and family into which we’re born and in which we grow up.

But, if you’ve been paying attention you’ll not that I said a little earlier that these are hardwired processing systems which derive from genetic information passed on from generation to generation, and if that the case, how can they hardwired (i.e. fixed and immutable) and yet cope with the many different moral outlooks that we find in different cultures and societies at the same time. Surely these systems can;t be both fixed and mutable at the same time.

Well, in fact they can, to some extent, and to understand why you’ll have to start by disposing of a couple of myths and misconception about the brain and how it works.

For example, you may think, as a matter of common knowledge and conventional wisdom, that we’re all born with all the brain cells (neurons) we’ll ever have and that that’s because the brain cannot grow new cells, certain not to replace one’s damaged or lost to injury, illness or rather too many heavy nights down the pub…

..and you’d be wrong because we’ve known for quite a while that there are two particular areas of the brain, the hippocampus and the denate gyrus, where we continue to create new brain cells not only after we’re born but right the way through into adulthood – and new evidence suggest this may also be occuring in other areas of the brain as well – and its damn good job that we do because the hippocampus, in particular, plays a key role in the formation and storage of memory, so if we did go on creating free neurons there then there’s every chance we’d all have the memory capacity of a goldfish, and where would be then.

You may also have got the idea that the brain somehow stops ‘developing’ in early childhood – at somewhere around two years of age. Give or take the hippocampus and dentate gyrus, what’s meant by the brain ceasing to develop at this stage in life is that it was thought that the internal structure and organisation of the brain became fixed at this point in time, but for losing a few neurons here, so the brain you’ve got once you hit two years old is everything you’ve got to work with for the rest of your life.

Again, its turns that that’s not quite true.

For one thing the development of the brain’s structure and organisation in the two years following birth is a bot more complicated than most people realise – for the first six months or so we actually develop many more neural connections that we’ll ever need after which we lose a large proportion of them, the one’s that prove to be redundent. If that’s all very new to you, then don’t worry about it. That the brain develops in this particular way is not that widely known or understood by the wider general public, outside of a few ‘groups’ where this information does crop up. If  you’ve got a child who has autism or has been evaluated for a possible autistic spectrum disorder then you may have run accross this information because the point at which the brain starts ditching redundent connections is about the same time that the first obvious indicators of autism become apparent, which has led some to propose that the two may be somehow associated.

(Whether they are or not is another matter but at least this suggestion makes sense, unlike the whole farrago over the MMR jab).

The other people, outside psychology, neuroscience and related disciplines, who tend of picked up on this aspect of neural development tend to the be the kind of over-anxious middle class parent who also think that putting a set of speaker on their bump while pregnant and blasting the little mite with Mozart and regaling them with readings from the collected works of Proust at the age of three months is giving their kid the best possible start in life and may even turn them into some of prodigy. If that’s you, then while exposing your kids to language early in life, by talking to them, is undoubtedly beneficial, the Proust is a bit excessive – stick to Winnie the Pooh and The Very Hungry Caterpiller, its works just as well and its damn sight more fun to read if you’re a parent.

Anyway, after what we’ve already learned about the business of creating new brain cell, you shouldn;t be too surprised to discover that the structure and organisation of the brain doesn’t actually stop developing at two years of age, well not all of it – but don’t feel too put out at having got that one wrong because this is all pretty new and, he way things are going, a discovery that looks set to alter our understanding of the human brain as fundamentally as relativity and quantum mechanics altered our understanding of the nature of the university. This is ‘big science’ in every sense of the word and it’s called ‘neuroplasticity‘.

Until fairly recently, it was widely thought, even by neuroscientists, that the structure and organisation of the lower brain and neocortex, the areas of the brain which deal, primarily, with learning and memory, became fixed and immutable during childhood, and again it turns out that this was wrong and that the structure and organisation of these areas of the brain not only continues to develop into adulthood, but that that this ongoing development is influenced and directed by the environmental stimuli that the brain receives from the outside world.

The answer to the age old argument about nature and nurture turns out to be both, and the interaction between the two are far more complex that anyone previously thought possible because when we’re learning then, at the same time, we’re also restructuring and reorganising our brain in the process.

This explains one of the big ‘puzzles’ about learning about learning itself because it explains how, and why, complex and information intensive skills, like reading, which we find difficult to master to begin with, will become, with enough time and practice, tasks we carry out without even thinking about or being consciously aware what we’re doing. The truth is thst once we’ve learned to read and mastered the skill to a pretty high level, then we’d don’t consciously think about the task of reading itself, we just point our eyes at the page and away we go, pausing only if we run across a word we don’t understand and for which we cannot nfer some kind of reasonable meaning from the context in which it appears in the text we’re reading.

How we achieve that particular feat has, in neurological terms, always been a bit of puzzle up until now. Before the discovery of neuroplasticity it was thought that it might all rely on the biochemical or bioelectrical connection stength between the neural connections used to carry out a particular task, so that the more you did that task, the stronger the connection became. The trouble is, we never did managed to find any significant evidence to support that theory and any other avenues we could think of, at the time, we hampered by the belief that the brain lost the capacity to alter its structure and organisation during childhood, ruling that out as a way of learning and attenuating skills that we would only begin to encounter and acquire after the point at which the structure of the brain became fixed.

Now we find that the key areas of the brain that we’re most concerned with don’t become fixed in the way we thought they did and that learning is also a process of ‘re-wiring’ the brain, altering its structure and organisation in response to environmental stimuli, the information we process in order or learn.

That explains, in neurological terms, how we learn to read and why a task, to begin with, takes a considerable amount of conscious thought  and effort, which is actually a rather slow and labourious way of doing things, becomes, over time, a skill we exercise with almost no effort at all.

It also explains how the genetically-derived ‘black box’ processing systems that take most of the effort out of everything from processing language to making moral choices, become set up for the primary language spoken in the household or cultural into which we’re born or primed with our culture’s moral values. what genetics provides are the basic, universal, processing systems but. up to the point at which we’re born, these systems are purely generic in their capabilities. The language system ‘knows’ how to decode auditory information and process it into imtelligible language, but what it doesn’t know, until we’re born, is exactly which language it will need to process. Only after we’re born and people start yabbering in our general direction, is the system configured for English, French, Hindi or Chinese and the parameters it needs to start processing language automatically are set by the information it gets from the external environment.

There – in full – is the neurological model that underpins Chomsky’s work.

As for the morality ‘black box’, same basic principle – genetics give us the core processing system, and the information we obtain about the nature of right and wrong we get from the external environment in which we live configures the system to spit out ‘instinctive’ responses that, more or less, fit in with the values pick up on and are we’re taught by those who surround us during our formative years.

And so, we come all the way back to dyslexia, for which we now have a viable neurological model that fits the available evidence, because we also have a viable neurological model for reading and for how we learn to read.

What we have are some genetic elements, the ‘black box’ systems that handle and speed up most the basic processing but which require additional information from the external environment in order for them to be configured for processing a particular language and, when it comes to reading, for the symbols and symbol arrangements that represent that language in a visual form. To read we’ve not only got to make use of those systems, but we’ve also got to build the neurla pathways and connections needed to join them all together in a manner which ensures that they operate as efficiently and effectively as possible, hard-wiring our brain for reading in the process.

Looked at as a system, and not just in terms of its individual components, which is what most of the existing theories which try to explain dyslexia attempt, we have an extremely complex system, and perhaps the best evidence of how complex that system is comes from very recent neuroimaging study which found that a native English speaker reading an English language text actually uses different areas of the brain while reading than those used by a native Chinese speaker reading a Chinese language text, which may sound a little odd as we’ve talking about universal language system, but makes perfect sense when you consider that we represent the English language, visually, using groups made up of only 52 basic symbols (allowing for upper and lower case) written horizontally on the page from left to right. Chinese, on the other hand, is written vertically and uses individual symbols, not groups, drawn from a lexicon which, in its unabridged form, runs to over 40,000 symbols although, in practice, a knowledge of 2,000 symbols is considered to amount to functional literacy while 6-7,000 would put you into the category of being well-educated. The obvious inference is that the differences observed in the neuroimaging study mirror the orthographic differences in the two languages, each of which places different information processing demands on the reader; a reader whose brain, as a native speaker of the language, is wired specifically to process that language.

What this leads us to is a clear prediction that there will two, and maybe three basic types of dyslexia.

One will be a genetic form which affects one or more of the ‘black box’ processing systems, causing it either to function inefficient or maybe even fail to function at all. This is the type that will prove largely intractable to conventional teaching methods an environmental interventions because the elements of these systems that a derived purely from genetic information cannot be ‘fixed’ or modified by the brain. This does not, however, mean that an individual with this type of dyslexia will not be able to read at all, rather the brain will attempt bypass the fault using the conscious abilities of the brain to compensate for the loss of function, much as those same abilities are used to enable us to read while we’re going through the process of learning to read.

For this type of dyslexia, educational interventions may be of some limited help – if nothing else you can teach various coping strategies to children with this type of organic problem and help them to find way to work around the difficulties they cannot fully overcome, but there’ll always be some degree of impairment in reading ability, even if, with hard work and effort, the overall impact on their life and prospects can be minimised as much as possible.

The second (and maybe third) type of dyslexia stems from delays and faults in the process of hardwiring the brain for reading – whether there are two distinct type of dyslexia here, or just one, depends on whether you consider the business of setting the parameters of the black box systems to be an intrinsic part of the general learning/hard-wiring process or a distinct component of the overall system in its own right – and this is where its gets interesting. You see, the key to making this hard-wiring work lies in the brain receiving the environmental stimuli it needs to make the process of building the relevant neural connections happen as it should, and this suggests that there are not one but two mechanisms that could delay or give rise to faults in this process.

One would be an organic, and probably genetic cause – which gives rise to delays in the rate at which the hard-wiring of the brain occurs, even though the individual receives the same degree of environmental stimuli that other children get, children who experience no significant problems when to learning.

The other, would be purely environmental – a lack of appropriate stimuli as would be found in families where reading is anything but the norm.

(And, of course, some kids may get a double-helping by having both the genes which cause an organic delay and a pretty crappy homelife to contend with).

Drawing a neat dividing line between the two types is, given where we are currently in terms of the limitations of neuroimaging and MRI scans) somewhere getting on for impossible, but we can a couple of useful predictions here.

One is that, regardless of whether the hold-up in hard-wiring the brain for reading is organic or environmental in its origins, both should respond to increasing the level of environmental stimulation and providing a better quality of stimulation. Educational interventions should work pretty well in these cases, and as there’s plenty of evidence to support that contention that the closer a written language maps to its phonemic characteristics the easier it is for a native speaker to learn (as is the case with Spanish and Italian), so should the use of synthetic phonics.

The other prediction we can make is the on that those seeking to sift the deserving from the undeserving really aren’t going to like at all, because while both the organic and environmental types of delay should respond to educational interventions – oh, and I should note that the delayed wiring hypothesis, of course, accounts for evidence of reading patterns and errors consistent with younger children in kids currently diagnosed as having dyslexia – they only way in which you can make a clear distinction between the two causal types is after the fact because you would expect that in those children where a general lack of support and appropriate stimuli is the sole cause of the problems you would somewhat more rapid progress once the interventions are in place that those who’re try to swim uphill against delays arising from an organic problem, but you can only assess that after the intervention has been put in place. While we might be able to argue, with a degree of confidence that if a child has a good home enviroment, attentive and supportive parents, and is putting the same effort as other kids in trying to learn to read, and still not making much headway, then we can be pretty sure that we’re looking at a kid with dyslexia, when it comes to kids who don’t get those same benefits its impossible to be sure whether the cause is purelly environmental or whether the environmental issues the child faces masks an underlying organic cause.

In that sense, the fact that we cannot pin down dyslexia to a single, uniform, set of symptoms evident in all children with the condition is less a problem and more a feature of the condition, and a useful one at that because, treated correctly, there is no justification whatsoever for writing a child off simply because they find learning to read a rather more difficult proposition that their classmates.

And that, dear reader, is how you do science.

When you run into a situation in which the some of the evidence seems not to support the current theory (or theories) then what you do is look at the evidence and formulate a new hypothesis, one that accounts for and explains the available evidence and makes predictions that can be tested experimentally.

Which is what (hopefully) I’ve done here…

What you don’t do, however, is simply give up and announce to the press that something doesn’t exist.

That’s just bad science.

9 Comments leave one →
  1. January 19, 2009 10:01 pm

    A friend of mine just emailed me one of your articles from a while back. I read that one a few more. Really enjoy your blog. Thanks

  2. samedifference1 permalink
    January 19, 2009 11:20 pm

    Thanks for commenting, Mike. I’m glad you enjoy my blog!

  3. Maggie D permalink
    January 21, 2009 10:18 pm

    Well, that’s how you do partial science.

    You’ve left out a large chunk about how the various methods of teaching reading will create different neural pathways leading to activation of different parts of the brain. Read up a bit more on the science behind reading instruction…

    And you’ve put far too much emphasis on home environment, forgetting that correlation does not equal cause. Everyone was illiterate at one point in history. How did a world full of illiterates manage to turn into a world where a very large proportion of its inhabitants are literate? Having a house full of books and reading to your child may encourage the practise of literacy skills, but it doesn’t cause them.

    Dyslexia is a symptom, not a condition.

  4. October 3, 2009 11:12 pm

    Here is an informative article on the relationship between auditory and visual spelling strategies:

  5. Kirk permalink
    July 21, 2012 2:36 pm

    Brilliant , I am a dyslexic completing a masters degree on this subject and that of entrepreneurs .. food for thought . thanks for writing it

  6. November 30, 2015 7:16 pm

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