Why is developmental dyslexia rare among people who speak Italian and morecommon among speakers of English or French?

The prevalence of developmental dyslexia varies among different languages due to the complexity of their orthographic systems.

1. Orthographic Complexity: Orthography refers to the conventional spelling system of a language. English and French have deep orthographies, meaning there is not always a one-to-one correspondence between sounds (phonemes) and the letters (graphemes) that represent them. This complexity can make it more difficult for individuals with dyslexia to decode words, leading to a higher prevalence of dyslexia in these languages.

2. Phonemic Awareness: Italian, on the other hand, has a shallow orthography. This means that there is a clear one-to-one correspondence between sounds and letters. This transparency makes it easier for individuals to develop phonemic awareness, the ability to hear, identify, and manipulate the individual sounds in spoken words, which is a crucial skill in learning to read.

3. Learning to Read: Because of the transparency of the Italian language, Italian children often learn to read faster than English or French children. This early success can help to mitigate the effects of dyslexia.

4. Diagnosis: The criteria for diagnosing dyslexia often involve a discrepancy between a person's reading ability and their expected reading ability based on their overall intelligence. Because reading is generally easier in Italian, a person with dyslexia might still be able to read at an average level for their age, making it less likely that they will be diagnosed with dyslexia.

In conclusion, the orthographic complexity of a language can significantly impact the prevalence of dyslexia among its speakers.