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

5. The development of fluency in English

Neurodevelopment and Neurodevelopmental Disorder

continuing right hemisphere involvement.

word sequences.

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comprehensive definition of fluency:

The American focus on the development of reading proficiency has been farranging and often perplexing, perhaps due to the intricacies of the English language. It has been considered that the cognitive processes underpinning reading ability may be differently involved in producing the symptoms of Developmental Dyslexia, depending on orthographic transparency [29]. Converging data from a variety of neurobiological investigations, but especially from functional magnetic resonance imaging, support the current belief that there are differences in the temporo-parieto-occipital brain regions between dyslexic and nonimpaired readers. Goswami [62] found that analysis of results from different technologies, including PET, fMRI, MEG, and EEG using different research questions, consistently show that children with Developmental Dyslexia display hypoactivation of crucial parts of the network of areas involved in word recognition and an atypical pattern of

The neurobiological origins of fluency can actually be seen in the early work of physiologist, Donald Hebb. In 1950, he proposed the concept of unitization when he observed patterns of cells in the visual cortex activating together after multiple exposures to novel visual stimuli [63]. LaBerge and Samuels went on to apply this idea to more complex visual levels such as familiar letter patterns, and in other modalities such as phonological representations. They focused on the automaticity of processing that decreases response time in learning and reading and is believed to increase the neurological resources allocated to comprehension [64]. American educators have historically used fluency as a measure of reading performance and a precursor of superior comprehension, but continue to fail in developing instructional exercises that improve reading speed, especially for those with specific reading disabilities. The expectation is that students will read fluently as a function of age and experience. Oral reading inventories and running records of reading performance commonly measure fluency as the rate and accuracy of oral reading and ignore the other aspects of fluency, particularly the contributions of lower level subskills: graphological features of letters, orthographic regularities of letter combinations, the semantic features of words, and the semantic-syntactic constraints of

Ultimately, Kame'enui, Simmons, Good, and Harn suggested a developmental conceptualization of fluency that included the building of proficiency in foundational component skills of reading, effectively merging the influences of skill devel-

proficiency [65]. It is this continuum that Wolf and Katzir-Cohen refer to in their

"In its beginnings, reading fluency is the product of the initial development of accuracy and the subsequent development of automaticity in underlying sublexical

opment with processing speed and accuracy into a continuum of reading

process, lexical processes, and their integration in single-word reading and connected text. These include perceptual, phonological, orthographic, and morphological processes at the letter, letter-pattern, and word levels, as well as semantic and syntactic processes at the word level and the connected text level. After it is fully developed, reading fluency refers to a level of accuracy and rate where decoding is relatively effortless; where oral reading is smooth and accurate with correct prosody; and where attention can be allocated to comprehension." [66] Since the development of fluency is founded in every process and skill used in reading, Kame'enui [67] advises that it also requires an increase in proficiency and speed in every underlying component. It seems obvious that failure to acquire these processes and skills would result in critical and persistent reading disabilities.

Researchers have been diligent to identify the progressive neurodevelopment of those underlying processes. It is clear that Frith's 1997 phonological deficit hypothesis which suggests that Developmental Dyslexia results from an underlying phonological impairment, and accounts for a wide range of behavioral symptoms associated with dyslexia, especially lexical retrieval and verbal short-term memory, has been thoroughly validated [68].

Further, the issue of general intellectual ability has been explored with regard to phonological processing. Although the 2004 reauthorization of the U.S.'s Individuals with Disabilities Act mandates that states can no longer require school districts to use IQ tests to identify individuals with learning disabilities [69], the majority of schools and school psychologists still rely on the discrepancy between reading achievement and IQ to define dyslexia [70]: requiring that reading skill should be significantly below the level expected given an individual's IQ. Tanaka et al. used fMRI, univariate, and multivariate pattern analysis to observe whether differences in brain activation during phonological processing that are characteristic of readers with dyslexia were the same or different in dyslexic children with poor reading ability who had high IQ scores (discrepant readers) and in dyslexic children with poor reading ability who had low IQ scores (non-discrepant readers) as compared to the phonological processing of typically developing readers [71]. The results show that discrepant and non-discrepant poor readers exhibited similar patterns of reduced activation in brain areas such as left parieto-temporal and occipitotemporal regions; there were no reliable functional brain differences between the two types of poor readers. The validity of the discrepancy definition of dyslexia is called into question. Even though the discrepancy criterion may be intuitively appealing, its strict application would deprive non-discrepant children of the educational interventions that could promote their advancement in reading.

American researchers have also found distinctions in the use of RAN for identifying impaired processing. Using multi-variant analysis of the results of a battery of reading skills measures of 123 dyslexic 2nd and 3rd graders, Katzir et al. found that rapid naming, orthographic pattern recognition, and word reading fluency moderately predicted rate, accuracy, and comprehension of connected-text reading, while phonological awareness contributed only to the comprehension dimension of connected-text reading [72]. The unanticipated result that rapid naming was more related to reading speed than phonological awareness may help explain the limited success of phonology-based reading intervention programs for achieving improvements in fluency and comprehension.
