Orthographic Depth

The degree of consistency in the relationship between letters (graphemes) and sounds (phonemes) in a writing system. Languages with shallow or transparent orthography — like Finnish, Spanish, and Italian — have highly consistent letter-to-sound mappings, meaning words are generally spelled as they sound. Languages with deep or opaque orthography — like English and French — have many inconsistencies and irregular spellings. Orthographic depth directly affects the manifestation and severity of dyslexia: English speakers with dyslexia produce more widespread spelling errors because the same sounds can be represented by many different letter combinations. This concept is important for accessibility practitioners working with multilingual content, as dyslexia support strategies may need to vary by language.