Dyslexia exists in all cultures and all languages. However, it does not impact learners in every culture in equal measure; the severity of dyslexia’s impact partially depends on the language a person is learning to read.

It All Starts With the Phoneme

The logic underlying writing systems is simple: Spoken languages use sound (phonology) to represent meaning (semantics); writing systems represent spoken languages; therefore, writing systems represent sound (phonology) and meaning (semantics). Writing systems are fundamentally similar because they are all solutions to the problem of representing sound and meaning in visuographic form. (Seidenberg, 2017, p. 46)

The thousands of languages of the world may feel vastly different, but when it comes to their written forms, they are remarkably similar. For starters, the characters in most writing systems are of roughly equal complexity. Researchers analyzed 115 writing systems and discovered that, with very few exceptions, most characters are created using two to four strokes (marks made without lifting the pencil), regardless of language (Changizi & Shimojo, 2005). While they look quite different, characters are not more or less complex in any given language. This makes sense given the need for economy of time when writing.

There are many other similarities among written languages. Writing is linear (left to right, right to left, or top to bottom) and often utilizes spaces between words. Most systems use punctuation and diacritics to add information, such as timing, tone, accent, inflection, or intonation. But the most important similarity is not how writing is conveyed, it’s what is being conveyed.

As Seidenberg points out (see the opening quotation above), each language strikes a balance between representing sounds and representing meaning. While some languages use an alphabet (where letters may represent only consonants, like in Arabic or Hebrew; both consonants and vowels, like in English or French; or consonant-vowel pairs, like in Thai), others, like Japanese, use a syllabary to represent syllables. Still others, like Chinese, use characters that represent entire words. Each language has developed an imperfect compromise designed to convey both sound and meaning at the same time. For alphabetic languages like English, the magical element that allowed modern languages to represent sound was the invention of the phoneme.

A phoneme is the smallest spoken unit of sound in a language. The need to write spoken words down required that writing systems develop notations to represent the approximated sounds in words. In alphabetic-type languages, alphabets were born.

The first task a child has when being taught to read is to understand that words can be broken apart into these smallest sounds. This understanding is called phonemic awareness. Additionally, a child must learn that the symbols on the page represent the sounds of the spoken language. This is known as the alphabetic principle. Once this connection is made, the work of learning those letters and their sounds can begin in tandem with learning the spelling system.

What’s /Luv/ Got to Do With It?

The regularity with which spelling (or orthography) represents sounds varies greatly from one language to the next. Some languages, like Italian, Finnish, or Spanish, have very close matching between letters or groups of letters (graphemes) and sounds (phonemes). For this reason, they are said to have a transparent or shallow spelling system. Perfectly transparent languages are one-to-one in both directions: a grapheme represents only one sound, and each sound is represented by only one grapheme.

Other languages, like English, have some letters and letter pairs that represent more than one sound, as well as some sounds that can be represented by more than one letter or group of letters. These languages are said to have an opaque or deep spelling system.

The English language has 26 letters and roughly 44 sounds, depending on dialect and articulation. While there is no agreed upon set of English graphemes, one analysis found 89 primary graphemes with 138 correspondences to English sounds (Brooks, 2015). Beyond that, the analysis identified nearly 200 additional graphemes representing “oddities” and low-frequency spellings. Obviously, English has a deep orthography that is not very transparent.

To make matters worse, English also has a complex syllable structure to accompany its complex spelling system. Multi-letter graphemes, context-dependent rules, irregularities, and morphological effects make learning to spell in English an even greater challenge (for example, consider the pronunciation shift and spelling change from the word nature to the derived word natural).

The Effect of English on Instruction

Due to the complexity of English spelling and syllable structures, it simply takes longer for children to develop accurate reading of words in English than in other languages. For comparison, consider a study of European orthographies (studied languages are listed in Figure 1). While students of all languages demonstrated understanding of letter-sound correspondences (above 90% accuracy) after one year of schooling, Seymour and colleagues (2003) estimated that it takes 2.5 years longer for learners of English to master reading familiar words and simple pseudo-words than for students learning transparent and neutral languages. Indeed, at the end of grade 1, the percentage of word reading errors in European countries demonstrates the dramatic effects of language transparency/opacity: Germany (3%), Italy (5%), Spain (6%), France (28%), Denmark (29%), and England (67%). It is no wonder that much of the focus and contemporary research on dyslexia has been conducted in the U.S., Great Britain, and Denmark.

European Languages by Orthographic Depth and Syllabic Structure
  Transparent spelling Somewhat transparent Neutral Somewhat opaque Opaque spelling
Simple syllables Finnish
Portuguese French  
Complex syllables  
Danish English

Figure 1. European Languages by Orthographic Depth and Syllabic Structure. Adapted from Seymour, Aro, and Erskine (2003), Table I (p. 146).

Note: Figure 1 represents the relative difficulty of learning to read words along two dimensions, depth of the spelling system and syllable complexity, among various European languages. Languages in bold type are associated with the word reading accuracy data (percentage of word reading errors at the end of grade 1) presented by country in the preceding paragraph.

A hallmark of dyslexia is the impairment of phonological processing. Learning to master the English spelling system is significantly more difficult than that of many other languages, requiring years more instruction and practice. Consider that the data above describes typical readers. If it takes a typical reader 2.5 years longer to master reading English words compared to Italian or Spanish words, how much more critical are the early identification and effective instruction and supports for a dyslexic reader? For this reason, it is imperative that educational systems:

  • Identify and monitor students who are at-risk for dyslexia as early as possible
  • Ensure that learners with dyslexia receive effective early reading instruction that addresses phonemic awareness, phonics, and fluency
  • Provide effective and sustained intervention supports until accurate and automatic word reading mastery is achieved
To learn more about dyslexia and the use of Read Naturally programs to support learners with reading disabilities, see our white paper, Dyslexia and Read Naturally.

Note: Highlighting the compounded challenge of dyslexia and English orthography on the learning experience of students in no way minimizes the challenges that dyslexia presents to individuals regardless of languages spoken. For example, Paulesu et al. (2015) confirmed that while dyslexic students in a transparent language (Italian) did better on reading tasks than students in opaque languages (French and English), all readers with dyslexia were impaired in phonological tasks compared with controls and exhibited the same reduced activity in the language network of the left hemisphere of the brain.



Brooks, G. (2015). The graphemes of written English. In Dictionary of the British English Spelling System (pp. 253–265). Open Book Publishers. https://books.openedition.org/obp/2190

Changizi, M. A., & Shimojo, S. (2005). Character complexity and redundancy in writing systems over human history. Proceedings of the Royal Society B: Biological Sciences, 272 (1560), 267–275. https://doi.org/10.1098/rspb.2004.2942

Paulesu, E., Démonet, J.-F., Fazio, F., McCrory, E., Chanoine, V., Brunswick, N., Cappa, S. F., Cossu, G., Habib, M., Frith, C. D., & Frith, U. (2001). Dyslexia: Cultural diversity and biological unity. Science, 291 (5511), 2165–2167. https://doi.org/10.1126/science.1057179

Seidenberg, M. (2017). Language at the speed of sight: How we read, why so many can’t, and what can be done about it. Basic Books.

Seymour, P. H. K., Aro, M., & Erskine, J. M. (2003). Foundation literacy acquisition in European orthographies. British Journal of Psychology, 94 (2), 143–174. https://doi.org/10.1348/000712603321661859