Dyslexia them. To understand reading and how we


is a condition that many institutions have had difficulty in defining due to it
affecting people in many ways and severities. Dyslexia is a learning difficulty
which “interferes with the acquisition and processing
of language” (Gilchrist and Thompson 1997:5), which means people
affected by it struggle with reading and comprehending information that is second
nature to most. In this essay, I
will firstly outline the dual-route model of reading to understand how a person
with dyslexia has a disrupted reading ability. However, this essay will primarily
focus on outlining acquired dyslexia, and how its subtypes impact a person’s
ability to acquire and process language. I will then go on to discuss why these
subtypes have been proposed and come to a conclusion about how effective these
categorisations are.



is the processing of information and then attributing information into meaning.
“Anyone who has successfully learned to read has
acquired a mental-processing system that can accomplish such transformations”
(Coltheart 2005:6). People
with dyslexia have either never been able to perform such transformations, or
have had injuries sustained to the brain that have impaired them. To understand reading and how we do it, it is
important to understand this processing system. This process, can be exemplified
by the dual-route model of reading. This model is comprised of two routes and it
offers an explanation of the cognitive processes that take place allowing us to
process print into semantic meaning. The direct route, or, lexical route, “involves looking up a word in a mental lexicon containing
knowledge about the spellings and pronunciations of letter strings that are
real words” (Coltheart 2005:9). The direct route is required for the reading of irregular words. For
example, it would be necessary to read irregular verbs such as thrust, or spread.  This is because these
examples are not spelt phonetically, so the reader must rely on lexical knowledge
of the exceptional spellings of words to pronounce them. This semantic pathway develops
throughout life, increasing lexical knowledge throughout time. People with
acquired dyslexia may have had this normal development prior to having impairments
resultant of brain damage.

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Whereas, “reading via the nonlexical route makes no
reference to this lexicon, but instead involves making use of rules relating
segments of orthography to segments of phonology.” (Coltheart 2005:9). The
indirect route is needed for reading unfamiliar words and pseudo-words. “A pseudoword is a fake word
– that is, a string of letters that resembles a real word (in terms of its orthographic and phonological structure) but doesn’t actually exist in the language.”
Examples of such words include, cigbet, shum and dake. To
understand these words, it is not possible to rely on existing lexical
knowledge, because they do not exist in language. What is significant for the
reading of these words are the rules of grapheme-phoneme correspondences. This relates
to letters and letter strings which represent the individual sounds in language,
therefore readers must sound out the letters in pseudowords individually to be
able to process and read them.


I will now move on to discuss acquired dyslexia, its
subtypes and how they relate to the dual-route model of reading.  Acquired
dyslexia affects a person’s reading ability and can occur because of brain damage.
There are three subtypes types of acquired dyslexia and each one affects an
individual’s ability to read in different ways. Phonological dyslexia is one of
these subtypes. Those with phonological dyslexia will lack the phonological
awareness required for the successful reading of pseudowords, “Phonological awareness refers to the realisation that words
are made of a combination of smaller units (syllables and phonemes), and to the
ability to pay attention to these units and explicitly manipulate them.” (Ramus).
Thus, they cannot read via the indirect route of the dual-route reading model,
so they are incapable of making the connections for the rules of grapheme-phoneme
correspondence. However, there is no impairment in the direct route which means
they can read real words in a language, both regular and irregular. Moreover, people
with phonological dyslexia often have other phonological impairments. They will
struggle to identify rhymes or confuse them, for instance, they will pronounce pint the same way as you would pronounce
tint. This suggests that phonological
dyslexia is not just a result of grapheme-phoneme correspondence, but also a disruption
of phonological processing.



contrast, surface dyslexia is another subtype that is the opposite to phonological
dyslexia, It “typically arises from damage to the left
temporal lobe” (Plaut 1999:547). Within
this type of dyslexia those affected have no impairment to the indirect route,
so they have the ability to read regular words and pseudowords. Albeit, unlike
in phonological dyslexia there is an impairment in the direct route, meaning they
cannot read irregular words such as, read,
for instance. Additionally, “island will
be read as “iz-land,” yacht to rhyme with “matched,” and have to rhyme with
“cave.” Exactly this pattern is seen in some people whose reading has been
impaired by brain damage” (Coltheart 2005:10). Those with surface
dyslexia “exhibit an interaction of frequency and
consistency in word reading accuracy, such that low-frequency exception words
are pronounced disproportionately poorly, often eliciting a pronunciation
consistent with more standard spelling-sound correspondences (e.g., SEW read as
“sue,” termed a regularization error).” (Plaut 1999:547).


dispute of this, individual differences affect how severely people experience acquired
dyslexia, these can occur
“not only from differences in the amount of semantic
damage, but also from premorbid
differences in the division of labor between the semantic and phonological
pathways”. (Plaut 1999:548). Additionally, these categorisations are quite restricted, there is not
a perfect double dissociation between both surface and phonological dyslexia. Many
people with surface dyslexia can still read irregular words. This suggests that
these categorisations do not take into account individual differences and could
be considered outdated. There has been limited research into dyslexia,
especially in adults, this means that there is some confusion in diagnosis.



This brings me onto my next point of
outlining deep dyslexia. Symptoms of this type dictate that they are not easily
explained by the dual-route model of reading. “Aphasic patients with deep dyslexia present
with a number of generally co-occurring features or symptoms” (Coltheart
1980:22). Similar to those with phonological dyslexia, people with
deep dyslexia have an impaired ability of the indirect route, which again means
they are incapable of reading pseudowords. However, they also make semantic
substitutions, or semantic paralexias, as well. For example, someone with this type
of dyslexia would read the word duel but
say the word sword. This demonstrates “an almost
complete inability to derive phonology directly from print (i.e., read
non-words), reading accuracy is affected by imageability/concreteness (highly
imageable/concrete better than low imageable/abstract words) and by the part of
speech (typically, nouns > adjectives > verbs > functors).” (Graham
and Ralph 2000:141). This
highlights how words that are more concrete and imageable, as opposed to
abstract ones, are easier to form a more vivid mental picture of making them
easier to read. In continuation, people with deep dyslexia may have a damaged syntactic
processing ability, so they’ll struggle with reading function words (such as the, or, and) and make morphological
errors. It would be problematic to pronounce prefixes or suffixes, but the root
of the word would be correctly said so unreal
would be read as real.