3. A review of international studies and phonological processing/speed

International researchers have investigated many of the most important factors identified in fluent reading. In Dutch, Vaessen and Blomert found that RAN

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

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

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.

> Year Subjects- age or grade

Wimmer Germany 1993 Grades 2, 3, 4 German dyslexics attain high

Netherlands 1993 Mean age: 10.2 years Dutch dyslexics attain high levels

Norway 1996 Grade 3 Norwegian dyslexics attain high

1997 8 year olds English children seem more

6.9 years; Dyslexic: 9.1 years

Major findings

levels of reading accuracy but remain slow in processing speed.

of reading accuracy but remain slow in processing speed.

levels of reading accuracy but remain slow in processing speed.

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

impaired because of orthographic differences; German children had few problems with accuracy after the first year of instruction.

languages, except for Finnish [38].

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

Researchers National

Yap, Van der Leij

Bjaalid, Hoien, Lundberg

Landerl, Wimmer, Frith

93

origin of subjects

Breznitz Israel 1997 Normal mean age:

Germany, England

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

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

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 severely incapacitated with the lowest accuracy and reading rates.

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
