Literacy is today regarded as a fundamental skill that provides individuals the means to pursue knowledge and enjoyment independently. In modern day knowledge societies, literacy skills are a necessity. A UNESCO report on literacy states that literacy is pivotal for development at macro-levels of nations, regions and the world¹.The first step to literacy is the ability to read – possibly one of the greatest inventions of mankind.

It is almost impossible to fathom a world when humans were unable to read, yet the ability to read is only 5000 years old and is acquired primarily through instruction. The remarkable ability wherein sounds of a language are mapped to symbols, thereby providing a visual form to spoken language, forms the basis of reading.

In order to learn to read, regions in the brain learn to associate specific sounds with symbols (or letters), forming neural circuits between brain structures; the key mechanism underlying this process is “neuroplasticity”. Popularly known as “rewiring the brain”, neuroplasticity is a unique phenomenon wherein brain regions originally specialized for vision (the occipital cortex), for hearing (the auditory cortex)^II and language (the frontal cortex) connect together to form a new brain circuit (Figures 1 and 2). The rules that define this mapping from sound to letter are determined by the writing system for that language. This new circuit becomes easier and stronger with practice; similar to how a muscle in the arm or leg becomes stronger with regular exercise.

Reading requires two processes: one involving letter-sound (orthography-phonology) mapping, and a second, wherein entire text is directly accessed (semantic storage)^III. The first process requires the ability to decode, in that each printed letter of a word is first converted to its corresponding sound before accessing meaning. Acquisition of speech is therefore a prerequisite before one learns to read. However speech acquisition is a natural process whereas learning to read requires extensive instruction. This is because spoken language appears seamless to the listener, with no clues to its segmental nature. Thus, the word “mat” comprises of the sounds “m”, “aa” and “t”, but one hears the holistic word “mat” and not three separate sounds.

Letter-sound mapping, however, requires multiple skills, including developing an awareness that spoken language can be segmented into smaller elements (i.e., phonemes or syllables), identifying letters, learning the rules of how to print maps onto sound, recognizing whole words not only accurately but also rapidly (automatically), acquiring a vocabulary, and extracting meaning from the printed word(s). In case of words that are irregular, such as “yacht” or “champagne”, where the spellings do not follow the rules, the second process (semantic storage) is employed, wherein the reader looks up the printed word in the mental lexicon and reads the word aloud, and is followed by sound decomposition. Functional magnetic resonance imaging (fMRI), a noninvasive brain imaging technique to measure brain activity in different areas while performing different tasks, has revealed the different regions of  the brain involved in reading. (Fig. 2)

Dyslexia

The inability to acquire age appropriate skilled reading, despite adequate intelligence, education and sociocultural opportunity^IV is termed as dyslexia. Now attributed to a difference in brain wiring, with a possible genetic origin^v, dyslexia is reported to be the most common form of learning disability across the globe. Recent reports suggest incidence of dyslexia has reached alarming proportions and is believed to be between 10 and 15 per cent of people worldwide^VI. This means that at least 10 individuals in a group of 100 do not possess age appropriate reading skills. Given the importance of reading in today’s world, this can severely impact opportunity for children.

There is robust scientific evidence that early intervention in dyslexia can help children cope with reading deficits. Remediation capitalizes on the “neuroplasticity” of the brain and through continued practice of sound awareness games, children show remarkable improvement. However in order to identify the optimal remediation strategies, it is critical that dyslexia be assessed in the appropriate language and cultural setting. Thus of equal, if not greater, importance is the assessment of dyslexia. As discussed earlier, languages vary in the writing systems that they use to map letter to sound. Consequently, the writing system that a language uses affects reading acquisition because each system is based on a different set of symbolic relations and requires different cognitive skills^VII.

Thus, while there clearly exist common principles/processes for learning to read, since the underlying features and rules for mapping graphic forms of writing sound to the sounds of a language vary, it is crucial that dyslexia assessments are sensitive to these differences. The following section will describe the typical process of a dyslexia assessment and discuss a few key aspects to ensuring reliable and appropriate profiles of children.

Screening and Assessment

If a teacher or parent finds a child struggling with reading in the classroom, the following process may be initiated to assess for dyslexia, namely:

1. Screening for dyslexia

The screening of dyslexia typically consists of an appropriate research-based checklist of symptoms that may include questions on sound awareness, letter knowledge, memory, reading familiar words, sequencing of information, comprehension and sensory issues.

It is important that dyslexia assessments be developed such that they assess both the cognitive processes necessary for reading across languages – yet also accommodate the features of specific writing systems.

2. Assessment of dyslexia

The assessment of dyslexia, on the other hand, must be educationally, cognitively and culturally sensitive. It is crucial that the assessment be functional and detailed. Functional means it should identify the domains where there are challenges in learning and be detailed enough to provide information on the specific aspect of the domain that needs remediation. For instance, phonological processing is an important predictor of reading and can be assessed via tasks that involve rhyming, manipulating sounds and sequencing sounds. The assessment of dyslexia should be detailed enough to functionally identify “phonological processing” as the domain and rhyming or manipulation or sequencing as the specific feature that requires intervention.

Cultural Sensitivity in Dyslexia Assessment

The smallest identifiable unit of language is a grapheme. A writing system embodies a language by segregating it into a sequence of these graphemes. For instance, the English writing system is phonemic in that each grapheme is mapped to a phoneme. A large body of research has focused on characterizing reading deficits in alphabetic writing systems with a focus on English. These studies from alphabetic systems like English have shown that to acquire basic reading skills one must learn to map alphabetic characters (graphemes) to the basic sound segments in speech (phonemes) that they represent. Alphabetic words thus are predominantly read out by assembling fine-grained phonemic units, i.e., by assembled phonology^VIII and the best predictors for reading in alphabetic scripts have been phonological awareness and rapid naming.

A second example is Chinese which is morpho-syllabic in nature, that is graphic forms are mapped to syllables and each syllable can correspond to several different morphemes or meaningful units of language^IX. The graphic forms of Chinese are also visuo-spatially complex and rely extensively on memorization and visuo-spatial processing.

A third example is Hindi written in Devanagari, which is alpha syllabic, meaning that the basic phonological unit is a syllable mapped to a graphic form called “akshara”. That is, each letter represents a consonant with an inherent vowel. Aksharas in written form contain one or more consonant(s) and vowel that are often symbolically attached to each other by matras also called diacritics. These matras often precede and follow the core consonant and have an impact on visual manipulation of phonological units^X. Research has shown that reading in Hindi is predicted by vocabulary and letter knowledge.

In the absence of tests in different languages and writing systems, dyslexia assessment is often restricted to English, leading to inappropriate and incorrect assessment of the child.

It is important that dyslexia assessments be developed such that they assess both the cognitive processes necessary for reading across languages – such as phonological awareness and vocabulary – yet also accommodate the features of specific writing systems. This is especially important as the cultural environments in which literacy and reading are acquired vary considerably around the globe. With increasing immigration, multilingualism is now a global phenomenon^XI, resulting in an educational milieu in which literacy is acquired in multiple languages that belong to distinct writing systems. One such phenomenon is biliteracy, which is the acquisition of literacy skills in two or more distinct languages. Populations in such circumstances are required to learn to read a non-native language in addition to their native language. For instance, in a number of South Asian countries, educational policies dictate learning English along with the native language in school^XII. In most cases, the native language of the child rarely shares the writing system with English. In India for example, all children learn to read Hindi and English, and so for Indian children it is crucial that they be assessed in both languages. In the absence of tests in different languages and writing systems, dyslexia assessment is often restricted to English, leading to inappropriate and incorrect assessment of the child.

An attempt in this direction was recently made in India where the National Brain Research Centre developed dyslexia assessment batteries for the Indian languages Hindi, Marathi and Kannada. Known as the Dyslexia Assessment for Languages of India (DALI)^XIII, this battery consists of screening tools and dyslexia assessment batteries in Hindi, Marathi and Kannada, and will ultimately be extended to include all the languages of the Indian Constitution. It was supported by the Department of Science and Technology of the Government of India. Given that appropriate dyslexia assessment is the right of every child, it is important that such initiatives be undertaken as part of government policy. Only then can we work towards a world of universal literacy.

^I Education for All Global Monitoring Report (2006). Retrieved from http://www.unesco.org/en/efareport/ reports/2006-literacy/^II Dehaene S, Cohen L. Cultural recycling of cortical maps. Neuron. 2007;56(2):384-98.^III Coltheart, M. (1985). Cognitive neuropsychology and the study of reading. In M. I. Posner and O.S. M. Marin (Eds.), Attention and Performance X1 (pp. 3-37). Hillsdale, NJ; Erlbaum.^IV Rumsey, J. M., Nace, K., Donohue, B., Wise, D., Maisog, J. M., Andreason, P. (1997). A positron emission tomographic study of impaired word recognition and phonological processing in dyslexic men. Archives of Neurology, 54, 562-573.^V Eden., E., and Moats., L., (2002), The role of neuroscience in the remediation of students with dyslexia, Nature Neuroscience, Vol. 5 (1080-1084).^VI Norton, E., S.,  Beac, S., D., and Gabrieli, J., D.,(2015) Neurobiology of dyslexia, Current Opinion in Neurobiology,20 (73-78).^VII Coulmas, F., (1989) The writing systems of the world.  Journal of Linguistics, 26(1), 275-290.^VIII Coltheart, M., Curtis, B., Atkins, P., and Haller, M. (1993). Models of reading aloud; Dual route and parallel-distributed processing approaches, Psychological Review, 100, 589-608.^IX Tan, L. H., Liard, A. R., Li, K. and Fox, P. T. (2005). Neuroanatomical correlates of phonological processing of Chinese characters and alphabetic words: A meta-analysis, Human Brain Mapping, 25, 83-91.^X Rao., C. and Singh., N., C. (2015). Visuospatial complexity modulates reading in the brain. Brain and Language (141) 5-61.^XI Agnihotri, R. K., & McCormick, K. (2010). Language in the material world: Multilinguality in signage. International Multilingual Research Journal, 4, 55-81.^XII Deterding, D., & Kirkpatrick, A., (2006). Emerging South-East Asian Englishes and intelligibility. World Englishes,  25 (3),  391–409. ^XIII Dyslexia Assessment for Languages of India [2015), National Brain Research Centre, India.

Nandini Chatterjee Singh is a cognitive neuroscientist formerly at the National Brain Research Centre in India and now working as Senior Project Officer at UNESCO MGIEP. Her areas of research are language, literacy and music. Recently, research in her laboratory has focused on understanding how the brain learns to read multiple writing systems and the implications of this in the assessment of dyslexia. She champions the cause of cultural validity in dyslexia assessment and has developed the first screening and assessment tools for Dyslexia Assessment for Languages of India (DALI).