The Neurobiological Development of Reading Fluency DOI: http://dx.doi.org/10.5772/intechopen.82806

contributed uniquely and substantially to the development of word reading fluency from grade 1 to grade 6 in primary school students [24], and when both accuracy and speed measures were considered in French, readers with dyslexia displayed deficiency in word-level reading skills [25]. A similar speed deficit of lexical and sub-lexical reading was also suggested by findings in French dyslexic children. The suggestion here being that the sub-lexical route shares with the lexical one the initial processing of the letter string, but then the lexical processing applies graphemephoneme rules in a serial mode [26]. This deficiency in sub-lexical processing is also a crucial feature in American dyslexic definitions and treatment, a language system

Researchers have proposed that between English and German dyslexic children with the same underlying phonological processing deficit, the English children show more severe reading impairment because of differences in orthographic consistency [27]. Mann and Wimmer [28] assessed readers in English and German at the end of kindergarten, and regression analyses showed that the only significant predictor of reading accuracy and speed in English was phonological awareness. Initial studies in German children found few problems with accuracy after the first year of instruction in contrast to English-based research and led to a German-English dyslexia comparison [27]. However, the reading fluency deficit of German dyslexic readers (found for all types of reading tasks) was found to be highly

Extensive research with German and Italian dyslexic children found reduced reading fluency as the main dyslexic impairment [6, 31]. Impairment on tasks that require implicit phonological processing, such as those evaluating verbal short-term memory, has been identified most clearly in transparent orthographies such as Italian and German [32]. Italian is a relatively shallow orthography, characterized by a high consistency of grapheme-phoneme correspondences and a simple syllabic structure. Also there are few irregular words and non-homographic homophones [15]. In spite of this regular orthography, Italian children with Developmental Dyslexia still present with a relevant difficulty which is primarily a deficit in reading speed [33] markedly affected by stimulus length [34]. Tobia and Marzocchi worked to define the cognitive profile of Italian children with Developmental Dyslexia. They found that 43.7% of children with DD had a profile that included deficits in both verbal and nonverbal domains. Some measures (visual search, syllable blending, and syllable deletion) were not significantly different among the three groups: dyslexic children, typically developing children of the same age (CA) and a control group of younger children equated for reading ability. Phoneme blending

The viability of accuracy/fluency-based typology of reading impairments has been investigated in Hebrew by Shany and Share [2]. Using a full battery of behavioral assessments including "pointed texts" (with all diacritical vowel markings included) and "unpointed texts" (with partial vowel markings included), these researchers found clear processing differences between the performances of students identified as rate-disabled and those identified as accuracy-disabled. Especially for word reading, the doubly-disabled subgroup of students was the most

The Korean handwriting system is an "alpha-syllabic" orthography, called Hangul. There are 24 graphemes, 14 are consonants and 10 are basic vowels. Hangul graphemes consistently represent sounds with a one-to-one correspondence and are combined in a limited number of patterns [36]. In a study using Hangul, researchers investigated the association of RAN and regular/irregular words in 4- and 5-yearold Korean children and found that RAN was uniquely associated with reading ability of both regular and irregular words [37]. Other research examined the cognitive abilities that predict reading and spelling performance in Korean children

known for its irregular words and "exceptions to the rule".

Neurodevelopment and Neurodevelopmental Disorder

was the only variable that showed a large effect size [35].

severely incapacitated with the lowest accuracy and reading rates.

92

persistent [29] and hard to remediate [30].

in Grades 1–4. Park and Uno [36] found that the contribution of phonological awareness to Hangul reading accuracy appears to occur only during the first 2 years of schooling, and RAN speed significantly predicted word-reading accuracy only in Grade 1. Further, the results of path analysis revealed that receptive vocabulary contributed exclusively and substantially to Hangul word-reading accuracy in Grades 1–4. This is unusual in light of the accepted idea that vocabulary plays a more important role in reading in less consistent orthographies [17]. Park and Uno argue that these results may be due to characteristics of the Hangul writing system that support the decoding of two-syllable words based on partial decoding and knowledge of the phonological and lexical aspects of a known, corresponding spoken word. In this case, the strategies needed to read accurately and with speed in Hangul differ with expertise and reading experience. A recent cross-language investigation measured reading performance (both reading accuracy and fluency), phonological short-term memory, RAN, receptive vocabulary and non-verbal intelligence in grade 2 children in five European countries (Finland, France, Hungary, Netherlands, and Portugal). While it is often proposed that extensive familiarity with the words of a language affects reading performance, the results here suggest that vocabulary was not a unique predictor of reading accuracy and fluency in these languages, except for Finnish [38].

In conclusion, phonological awareness represents the main predictive factor in normal and disabled readers of different languages. However, it may be less relevant in consistent orthographies, especially for reading accuracy where language –specific patterns appear to exist [39]. Research in German [40], Dutch [41], Norwegian [42], Italian [33], Greek [43], Finnish [44], Hungarian [45], and Hebrew [46], shows that most dyslexics in these languages attain high levels of reading accuracy but remain slow. It is possible that orthographies that are relatively regular in their letter-sound correspondences such as the Arabic require rapid development of the "direct access route". Perhaps it is only with increasing practice that improvements in efficiency lead to the reliable use of "direct access processes". Consequently, it is unclear whether the sub-lexical route accesses semantics after the phonology is assembled, and it is still debated whether direct visual access can occur without phonological mediation [47]. See Table 1 for a time-ordered summary of the international studies cited regarding phonological processing.



4. A review of international studies and visual processing

International studies of phonological processing in time order.

Italy 2014 DD grp. Mean age:

Researchers National

Sprenger-Charolles

Csépe, Honbolygó, Paavo, Leppänen

Tobia, Marzocchi

Table 1.

95

origin of subjects

The Neurobiological Development of Reading Fluency DOI: http://dx.doi.org/10.5772/intechopen.82806

> France, Spain, England

Year Subjects- age or grade

Shany, Share Israel 2011 Grades 2, 4, 6 There are processing differences

Major findings

2011 7 yr. olds French dyslexics were weak in

Hungary 2012 Grades 2–4 Hungarian dyslexics attain high

9.76 years; Control grp. 9.82 years; RA grp. 7.38 years

Park, Uno Korea 2015 Grades 1–4 RAN speed significantly predicted

between rate-disabled and accuracy-disabled readers; the doubly-disabled readers had the lowest accuracy and reading rates.

word reading when both accuracy and speed were measured.

levels of reading accuracy but remain slow in processing speed.

Results show that 43.7% of Italian children with DD showed deficits in both verbal and nonverbal domains; phoneme blending was the only variable that predicted

word-reading accuracy only in Grade 1; receptive vocabulary contributed exclusively and significantly to word reading

reading disability.

accuracy.

An interesting element of learning to read in a regular orthography is the relative ease of attaining high levels of accuracy. Correct reading in transparent orthographies is already at ceiling level after the first year of formal instruction [5, 17]. The advantage of regular orthography was further documented in studies comparing a substantial number of regular European writing systems with English [5, 48]. Due to the transparency of the language system, visual processing deficits are often found to contribute to dyslexia. In a Norwegian study, Talcott et al. demonstrated the presence of visual processing deficits characteristic of poor readers in a sample of poor readers [49]. Finnish is one of the most regular alphabetic orthographies and dyslexia primarily means slow dysfluent reading, however a major dysfunction of the occipito-temporal reading circuit is suggested by a series of MEG studies with Finnish dyslexic adults [50]. A dysfunction of left occipito-temporal reading areas was also found in the cross-linguistic PET study by Paulesu et al. [51] which included dyslexic adult readers from the regular Italian orthography and from less regular orthographies of French and English. There is also a good deal of evidence that children with Developmental Dyslexia also experience difficulties in visuoattentional tasks [52], such as visual search [53], visual recognition [54], and lowlevel (occurring within the first 300 milliseconds of visual analysis) visual information processing [55]. Thai researchers examined the performance of good and poor 10 year-old Thai readers on visual processing and reading accuracy tests and found


Table 1.

Researchers National

Wimmer, Mayringer, Landerl

Zoccolotti, De Luca, Di Pace, Judica, Orlandi,

et al.

De Luca, Borrelli, Judica, Spinelli, Zoccolotti

Hutzler, Wimmer

Thaler, Ebner, Wimmer, Landerl

Zoccolotti, De Luca, Di Pace, Gasperini, Judica, et al.

Puolakanaho, Ahonen, Aro, Eklund, Leppanen, et al.

Cho, Mcbride-Chang, Park

Georgiou, Parrila, Papadopoulos

Landerl, Wimmer

Vaessen, Blomert

Ziegler, Bertrand, Tóth, Csépe, Reis, et al.

94

Finland, France, Hungary, Portugal, Netherlands

Mann, Wimmer Germany,

England

origin of subjects

Neurodevelopment and Neurodevelopmental Disorder

Year Subjects- age or grade

End Gr. 2

Porpodas Greece 1999 Grade 1 Greek dyslexics attain high levels

Italy 1999 11–15 years old Italian children with DD

Germany, Italy 2002 11–16 years old Reduced reading fluency is the

Germany, Italy 2004 13 yr. olds Reduced reading fluency is the

Germany 2004 8–11 years old Reading fluency deficit in German

Italy 2005 Grades 1, 2, 3 Reading speed deficits in Italian

Korea 2008 4 and 5 yr. olds RAN was uniquely associated with

Germany 2008 Gr. 1, 4, 8 Reading fluency deficit in German

Netherlands 2010 Grade 1–6 RAN contributed uniquely and

Finland 2007 3.5, 4.5, and 5.5 years old

Germany, Italy 1998 Beginning Gr. 1 and

Major findings

clearly in transparent orthographies.

reading speed.

2002 End of Kindergarten Phonological awareness was the

Impairment on verbal short-term memory has been identified most

of reading accuracy but remain slow in processing speed.

demonstrate primarily a deficit in

main impairment in German and Italian dyslexic children.

only significant predictor of reading accuracy and speed in

main impairment in German and Italian dyslexic children.

Dyslexic readers is hard to

children with DD are markedly affected by stimulus length.

Finnish dyslexics attain high levels of reading accuracy but remain slow in processing speed.

reading ability of both regular and

irregular words.

orthographies.

persistent.

fluency.

for Finnish.

2010 Grade 2 Vocabulary was not a significant

less relevant in consistent

dyslexic readers is highly

substantially to word reading

predictor of reading accuracy and fluency in these languages, except

2008 Grades 1 and 2 Phonological awareness may be

English students.

remediate.

International studies of phonological processing in time order.
