Word recognition:
Non-semantic dyslexia & Semantic memory disorder
Student: Arlette Ortiz
Teacher: Roberto Ferreira
Date: December 12, 2018
Non-semantic dyslexia and semantic memory disorder
Word recognition plays an essential role when children or an adult person is learning
to read. It helps them to recognize printed or spoken words, and then to turn these
words into sounds. But there are people that present impairments regarding
semantic processes, in consequence, word recognition does not work as good.
These people could be categorized within one of the three diseases relating to word
recognition; dyslexia, dysgraphia, and semantic memory disorders.
Recognition refers to the ability to identify an item as familiar. Additionally, word
recognition refers to the ability to recognize a word effortlessly. It also searches for
an explanation of how the information related to this word becomes available. Lexical
access plays an important role in word recognition, considering that when we see a
string of letters that is familiar, we know that this string forms a word, the meaning of
it, the plural form, and even how it is pronounced. Furthermore, Balota (1990)
mentions that in word recognition there is a process called the magic moment, which
alludes to that point in time when a person has recognized a word but does not have
access to the meaning yet. In addition, she claims that when words are presented in
related contexts, the meaning of the word may become available before it is
recognized.
Although many processes involved in accessing the meaning of a word are common
for visual and spoken word recognition, the main difference is that speech signal is
only available for a short period of time instead of written words that are available as
long as the reader needs it. As well as the similarities in the processes of recognizing
the meaning of a word, when there is brain damage, these impairments are also
similar. Damage in the left hemisphere generally results in dyslexia, but as this site is
involved in speech as well, dyslexia is frequently associated with impairments to
spoken language processing. Besides, semantic memory disorders are also related
to word recognition and damage in the left hemisphere.
Disorders related to reading are called dyslexia, and disorders related to writing are
called dysgraphias. Moreover, there are differences in the way in which a disorder is
produced. Acquired disorders could be a consequence of head trauma; on the other
hand, developmental disorders are a result of disruption in the development of a
particular function.
As it has been mentioned before, dyslexia is a language disorder and it can be
divided into four types. The first one is surface dyslexia, a patient who suffers from
this kind of disorder has a selective impairment in the ability to read irregular words.
Nevertheless, their ability to read regular words and nonwords is intact, as well as
the comprehension of word meaning. In addition, surface dyslexia has two subcategories, type I patients are highly accurate at naming regular words and
pseudowords; on the contrary, type II patients show some impairments in these
tasks. However, patients of both type have problems reading exception words.
The second type of dyslexia is phonological dyslexia. Patients have a selective
impairment in the ability to read pronounceable nonwords, called pseudowords. At
the same time, their ability to read matched words is preserved. Also, patients find
that irregular words are not harder to read than regular ones. The phonological
dyslexics that can pronounce some nonwords improve the reading of them if the
nonwords are pseudohomophones. They sometimes make derivational errors, where
they read a word as a grammatical relative of the target; additionally, they make
visual errors, in which they read a word as another with a similar visual appearance.
The third kind is deep dyslexia, which is very much alike phonological dyslexia.
Patients have difficulties in reading nonwords and grammatical, function words. As
phonological dyslexics, they make visual and derivational errors, but the main
characteristic is semantic paralexias when people produced a word related in
meaning to the target instead of the target. The imageability of a word is an
important factor to have success in reading. The easier it is to form a mental image
of a word, the easier is to read it.
By lats, the fourth kind is non-semantic reading. Patients have huge impairments in
retrieving the meaning of written words. Nonetheless, they could read aloud almost
any word also they could read irregular words and nonwords. In simplest words,
patients could read words without the comprehension of their meaning. A case study
conducted by Coslett (1991), suggests that people must have a direct route from
orthographic to phonology that does not go through semantics. The idea of a third
route model arises from the study of W.T a 30-year-old woman who had impairments
in the comprehension, writing, and repetitions of words of low imageability, yet she
was able to read those words accurately. The results of the research suggest that
“W.T. read by means of a third reading mechanism characterized by the activation of
a lexical entry in the auditory input lexicon and the subsequent activation of the
corresponding entry in the phonological output lexicon without semantic mediation”
(Coslett, 1991, p.438)
Several cases of non-semantic dyslexics have presented slightly different symptoms
among them. Aforementioned, there are patients with impairments in semantic
processing, but they are able to read aloud exception words correctly. On the other
hand, there are patients that suffer from a condition called “word meaning blindness”
(Lambon, Ellis & Sage, 1998) in which they show impaired comprehension of written
words, yet they auditory comprehension appeared to be unaffected. In this way,
when patients read the words aloud, they are capable of access to their meaning.
For instance, Gerhand (1999) reported the case of EW a 74-year-old woman who
presented non-semantic dyslexia. EW was administered several tests under three
categories; reading, comprehension, and implicit semantic processing. In the case of
reading, EW was asked to read aloud certain words which she read all correctly.
Nevertheless, when she was asked to define each word before read them, the
procedure had to be abandoned because she could not comply with it. Furthermore,
EW’s reading test showed that she was able to read aloud non-word and all words
without errors, but she seemed to be enabled to generate inner speech. This may
explain her tendency to read words spontaneously aloud. The last test related to this
category was visual word recognition. A list of words with non-words and words was
presented to her, and she was asked to place a tick next to each real word. The
results suggested that she was prone to accept orthographically legal non-words as
words.
In terms of comprehension, she was asked to discriminate printed words. A trial of
words was presented with the target one in bold printed, and the two others in
normal print, one of them was a synonym of the target one. At first, EW was
requested not to read aloud, and her results suggested chance performance. The
next time, she was allowed to read the target word aloud. Although the
improvements in abstract words were significant, there was not a huge difference for
concrete words. In addition, EW was administered a homophone definition task. She
was asked to define a printed word and then read it aloud. The first time, she could
only define one out of twenty words. The second time, she attempted to give some
kind of definition to six words out of twenty, despite the fact that three of these
corresponded to the word homophone.
In order to test the implicit semantic processing, a picture-word interference task was
used. EW was present 150 pictures under three conditions: picture alone, picture
accompanied by four semantically-related words, and pictures accompanied by four
semantically-unrelated words. When she named the pictures on their own, her score
was good, but when she named the pictures with related and unrelated words, the
results dropped a lot. The low score could be considered as a result of her tendency
to read the words aloud. Moreover, the lack of difference between the semantically
related and unrelated words indicated that during the processes there was no
contribution of implicit semantic processing.
Furthermore, semantic memory encompasses knowledge of objects, facts, concepts,
words and their meaning. In a similar way as dyslexia, semantic memory disorders
could be divided into two types; semantic memory disorder and episodic or
autobiographical memory disorder. As its name says, patients with semantic memory
disorder have impairments of knowledge under those conditions, and it is not
temporally specific; therefore, patients are not able to remember a particular time
when they acquired knowledge. In contrast, episodic memory is a personal collection
of temporally-specific events in different contexts. Hodges & Patterson (1997) state
that semantic and episodic memory must be interdependent, due to “general
knowledge must be acquired from specific episodes, and further specific experiences
are understood and encoded with reference to general knowledge.” (Hodges &
Patterson, 1997, p. 69)
As a case in point, Cipolotti & Warrington (1994) presented the study of a patient
who had marked naming and word comprehension difficulties. The patient called
DNR was capable of reading regular and exception words; however, he was not able
to comprehend them. Patients that suffer from progressive dementia often present
impairments of semantic memory including deficits of word comprehension (Cipolotti
& Warrington, 1994). DNR was a 67-year-old man who had problems in
understanding even simple common words and questions also his verbal recognition
memory was weak.
The investigation was focus on the relationship between his impairment of verbal
comprehension and his preserved reading skill. As same as EW, he was
administered four different test. The first test was called reading, writing, naming,
and definition, and was tested under four conditions: picture naming, reading aloud,
written spelling, and defining the word presented auditorily. The results showed that
he was better on reading condition than on naming and definition condition. His
spelling was not significantly worse than his reading, yet was significantly better than
naming or defining condition. Apparently, his failed in naming any items of the task
was because he was not able to identify some of the pictures.
The second test was reading and comprehension of picturable words, which
assessed DNR’s ability to read aloud and to define written words. The stimuli
consisted of 106 printed words, in which 53 were regular and 53 were exception
words matched for frequency, and syllable length. The patient was asked to read
aloud the single words and immediately after to define it. The results showed that
there is a considerable effect of word frequency. The definitions of the highfrequency words were almost perfect, in contrast, the definitions of the mediumfrequency and the low-frequency words were very poor.
The third test was reading and comprehension of regular and exception words. The
stimuli consisted of 96 pairs of regular and exception monosyllabic words matched
for frequency, length, and initial phoneme. The test only contained high and lowfrequency words. The results are similar to the previous test, his definitions for highfrequency words were almost flawless, whereas he presented impairment in defining
low-frequency words. In terms of reading, word frequency and regularity did not
affect his performance. To reaffirm the result obtained from the second test, he was
able to read almost perfectly regular and exception words.
The last test consisted in comprehension and reading of abstract and concrete
words. The aim of this test was to assess whether there was a significant
dissociation in his ability to define concrete and abstract words (Cipolotti &
Warrington, 1994). The stimuli contained 36 high concrete items and 36 low concrete
words matched for length and frequency. As in the second test, DRN was asked to
read aloud the single word presented and then defined it. He could define 52 % of
the concrete words and 80 % of the abstract words. Therefore, his ability to define
abstracts words is better than on defining concrete words.
The patient’s ability to read regular and exception words were preserved at all level
of word frequency, in contrast, his ability to define regular and exception words did
was affected by the levels of word frequency. Since DRN could read aloud exception
words that he could not comprehend, Cipolotti & Warrington (1994) suggested that
the integrity of phonological representation did not depend on their interaction with
the semantic system.
In conclusion, it is necessary to differentiate among the different subtypes of
diseases, considering that not all the patients present the same symptoms. In the
case of dyslexia, there are four subtypes, surface dyslexia, phonological dyslexia,
deep dyslexia, and non-semantic dyslexia. In the case of semantic memory
disorders, the two types are divided according to the impairment. A patient could
have impairment regarding semantic memory or episodic memory. Besides, the
similarities presented between non-semantic dyslexia and semantic memory
disorders are greater than the differences. Taking into consideration that both
patients are able to read words aloud without being able to understand their
meaning. Although patients with semantic memory disorders are able to define highfrequency words, this ability is affected at defining medium and low-frequency words.
It is also important to remark that even though dyslexia is a disorder that can be
detected in both adults and children, the studies were conducted on older people in
both cases. Therefore, there is a probability that non-semantic dyslexia and semantic
memory disorder are directly related, even more, if they have detected in the same
hemisphere, the left one.
Reference
Balota, D. A., D'Arcais, G. F., & Rayner, K. (1990). Comprehension Processes in
Reading. Mahwah, New Jersey: Lawrence Erlbaum Associates.
Cipolotti, L., & Warrington, E. (1995). Semantic memory and reading abilities: A case
report. Journal of the International Neuropsychological Society, 1(1), 104-110.
Coslett, H. B. (May 1991). Read but not write "Idea": Evidence for a third reading
mechanism. Brain and Language,40(4), 425-443.
Gerhand, S. (1999, October). Routes to reading: A report of a non-semantic reader
with equivalent performance on regular and exception words. Retrieved from
https://www.sciencedirect.com/science/article/pii/S0028393201000288
Harley, T. A. (n.d.). The Psychology of Language: From Data to Theory [4].
Hodges, J. R., & Patterson, K. (1997). Semantic memory disorders. Trends in
Cognitive Sciences, 1(2), 68–72.
Lambon, M. A., Ellis, R. A., & Sage, K. (1998, June 01). Word Meaning Blindness
Revisited.