4. A review of international studies and visual processing

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

a difference between the good and poor Thai readers in their performance on visual processing tests [56].

most compelling issue regarding fluency around the world may be that in spite of different orthographies and language regularities, commonly-used instructional interventions still do not result in lasting remediation for the majority of this population. See Table 2 for a time-ordered summary of the international studies

olds

men

adults

14 yr. olds

old children

adults

13 year olds

16 year olds

13 year olds

12 year olds

Israel 2013 Grade 4 There were no significant

2003 6, 7, 8, yr. olds found.

tests.

Children with DD show difficulties with low-level visual information processing.

Men with DD show difficulties with visuo-attentional tasks.

In a cross-linguistic PET study, a dysfunction of left occipitotemporal reading areas was

Reading accuracy in transparent orthographies is at ceiling level after the first year of instruction.

Visual processing deficits were characteristic of poor readers.

There is a difference in good and poor Thai readers in their performance on visual processing

MEG studies reveal a major dysfunction of the occipitotemporal reading circuit

First reports suggesting abnormalities of the lefthemisphere tracts that connect occipito-temporal brain regions with temporo-parietal and left inferior frontal areas.

Dysfluent readers showed underactivation of the left occipito-temporal region and increased activation in a left inferior frontal region.

Children with DD show difficulties with visual recognition.

Children with DD show difficulties with visual search.

or un-vowelized).

differences in reading accuracy or speed in dyslexic readers regardless of the text (vowelized

Researchers National origin of subjects Year Subjects Major Findings

Australia 1987 13 year

United States 1996 Adult

England, France, Italy 2001 Dyslexic

Norway 2003 12, 13,

Thailand 2004 10-year

Finland 2004 Dyslexic

United States 2005 7–

Germany 2006 14–

Italy 2008 9–

Australia 2010 7–

International studies of orthographic processing in time order.

Denmark, England, Finland, France, Germany, Greece, Iceland, Italy, Netherlands, Norway, Portugal, Spain,

cited regarding orthographic processing.

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

Sweden

Slaghuis, Lovegrove

Paulesu, Demonet, Fazio, Mccrory, Chanoine, et al.

Seymour, Aro, Erskine

Talcott, Gram, van Ingelghem, Witton, Stein, et al.

Kim, Davis, Burnham, Luksaneeyanawin

Salmelin, Helenius

Deutsch, Dougherty, Bammer, Siok, Gabrieli, et al.

Kronbichler, Hutzler, Staffen, Mair, Ladurner, et al.

Geiger, Cattaneo, Galli, Pozzoli, Lorusso, et al.

Vidyasagar, Pammer

Schiff, Katzir, Shoshan

Table 2.

97

Eden, Vanmeter, Rumsey, Maisog, Woods, et al.

Schiff et al., [57] examined the effects of orthographic transparency on the reading ability of fourth-grade children with dyslexia on two Hebrew scripts. In addition to documenting reading accuracy and speed, this study also investigated the role of vowelization in the reading ability of un-vowelized script among readers with dyslexia. These results showed that fourth-grade children with dyslexia read the vowelized script with less accuracy than that found in typically developing second-graders. Also, the children with dyslexia demonstrated no significant differences in the reading accuracy or speed between the vowelized and unvowelized scripts. However, for these readers with dyslexia, accuracy in reading both vowelized and un-vowelized words mediated the reading speed of un-vowelized scripts. These findings underscore the idea that if grapheme-phoneme conversion skills are flawed in Hebrew children with dyslexia, they are unable to use the vowelized script as a self-teaching mechanism for acquiring an autonomous orthographic lexicon that would enable future word recognition.

The hypothesis of poor phonological-orthographic integration suggests impaired neural connectivity between regions engaged by orthographic processes and regions engaged in phonological processes [58]. There are first reports suggesting abnormalities of the left-hemisphere tracts that connect occipito-temporal brain regions engaged by visual-orthographic processes with temporo-parietal and the left inferior frontal areas engaged by phonological processes [59]. Functional imaging findings- some with German dyslexic readers -show reduced reading related activation in a left ventral occipito-temporal brain region, which is assumed to function as an interface between high-level visual orthographic codes and phonology and meaning. As expected, dysfluent readers exhibited underactivation of the left occipitotemporal region of interest-ROI (engaged by fast word processing) and increased activation of the left inferior frontal ROI (engaged by phonological decoding) [60]. Voxel-based analysis showed that for fluent readers, extended activations were found in the left temporal cortex mainly along the superior temporal sulcus and in left inferior frontal and precentral regions. The left temporal activation extended into the supramarginal gyrus and inferior occipito-temporal cortex. More issues regarding neural connectivity will be investigated in depth later.

A fascinating example of an opaque and complex orthographic system used in India is found in the Urdu language system. There are 38 letters with no vowel letters, and diacritics, which serve as vowel markings in its script, are omitted. The graphemic system called Nastaliq is cursive, and is characterized by many to one mappings between graphic symbols and sounds. Further, the same letter is written differently in different positions in a word, [61] greatly increasing the possible variations of each letter. Most Indian children speak Punjabi as their first language, but Urdu is the national language and the language of the media. It is the medium of instruction at schools, and another first language for some children, depending on the social class. In all Pakistani schools, English is taught and evaluated as a compulsory subject from grade 1, but in Urdu medium schools, all subjects are taught in Urdu, and English is taught as a subject, and in English medium schools, all subjects are taught in English, and Urdu is taught as a subject. There are clearly differences in the instruction and informal practice of reading and writing the Urdu language in different settings. For both the control group and the reading disability group, both RAN letters and RAN digits significantly predicted fluency with RAN letters being the stronger predictor. For the control group, non-word reading was the most significant predictor of accuracy and RAN letters was the other significant predictor. For the reading disability group, only RAN letters predicted accuracy [61]. So even in a visually complicated, reading-in-a-second (or third) language, rapid naming is shown to be an important predictor of reading accuracy. However, the

a difference between the good and poor Thai readers in their performance on visual

Schiff et al., [57] examined the effects of orthographic transparency on the reading ability of fourth-grade children with dyslexia on two Hebrew scripts. In addition to documenting reading accuracy and speed, this study also investigated the role of vowelization in the reading ability of un-vowelized script among readers with dyslexia. These results showed that fourth-grade children with dyslexia read the vowelized script with less accuracy than that found in typically developing second-graders. Also, the children with dyslexia demonstrated no significant differences in the reading accuracy or speed between the vowelized and unvowelized scripts. However, for these readers with dyslexia, accuracy in reading both vowelized and un-vowelized words mediated the reading speed of un-vowelized scripts. These findings underscore the idea that if grapheme-phoneme conversion skills are flawed in Hebrew children with dyslexia, they are unable to use the vowelized script as a self-teaching mechanism for acquiring an autonomous orthographic

The hypothesis of poor phonological-orthographic integration suggests impaired neural connectivity between regions engaged by orthographic processes and regions engaged in phonological processes [58]. There are first reports suggesting abnormalities of the left-hemisphere tracts that connect occipito-temporal brain regions engaged by visual-orthographic processes with temporo-parietal and the left inferior frontal areas engaged by phonological processes [59]. Functional imaging findings- some with German dyslexic readers -show reduced reading related activation in a left ventral occipito-temporal brain region, which is assumed to function as an interface between high-level visual orthographic codes and phonology and meaning. As expected, dysfluent readers exhibited underactivation of the left occipitotemporal region of interest-ROI (engaged by fast word processing) and increased activation of the left inferior frontal ROI (engaged by phonological decoding) [60]. Voxel-based analysis showed that for fluent readers, extended activations were found in the left temporal cortex mainly along the superior temporal sulcus and in left inferior frontal and precentral regions. The left temporal activation extended into the supramarginal gyrus and inferior occipito-temporal cortex. More issues

A fascinating example of an opaque and complex orthographic system used in India is found in the Urdu language system. There are 38 letters with no vowel letters, and diacritics, which serve as vowel markings in its script, are omitted. The graphemic system called Nastaliq is cursive, and is characterized by many to one mappings between graphic symbols and sounds. Further, the same letter is written differently in different positions in a word, [61] greatly increasing the possible variations of each letter. Most Indian children speak Punjabi as their first language, but Urdu is the national language and the language of the media. It is the medium of instruction at schools, and another first language for some children, depending on the social class. In all Pakistani schools, English is taught and evaluated as a compulsory subject from grade 1, but in Urdu medium schools, all subjects are taught in Urdu, and English is taught as a subject, and in English medium schools, all subjects are taught in English, and Urdu is taught as a subject. There are clearly differences in the instruction and informal practice of reading and writing the Urdu language in different settings. For both the control group and the reading disability group, both RAN letters and RAN digits significantly predicted fluency with RAN letters being the stronger predictor. For the control group, non-word reading was the most significant predictor of accuracy and RAN letters was the other significant predictor. For the reading disability group, only RAN letters predicted accuracy [61]. So even in a visually complicated, reading-in-a-second (or third) language, rapid naming is shown to be an important predictor of reading accuracy. However, the

lexicon that would enable future word recognition.

Neurodevelopment and Neurodevelopmental Disorder

regarding neural connectivity will be investigated in depth later.

processing tests [56].

96

most compelling issue regarding fluency around the world may be that in spite of different orthographies and language regularities, commonly-used instructional interventions still do not result in lasting remediation for the majority of this population. See Table 2 for a time-ordered summary of the international studies cited regarding orthographic processing.


### Table 2. International studies of orthographic processing in time order.
