Reading skills of Japanese second-graders

Background: A few studies have explored the prevalence of dyslexia among children who speak Japanese as their native language by evaluating them individually by means of reading-based tasks. The present study was designed to clarify the frequency of suspected dyslexia among second-graders attending ordinary classes. Methods: The subjects were 40 children (22 males, 18 females; 7 years 4 months-8 years 4 months; mean age, 7 years 11 months) out of 182 second-graders at a public elementary school situated in a local city. Each subject underwent a monomoraic syllable reading task, a word reading task, a non-word reading task, and a short sentence reading task. Results: The scores on the four tests were not normally distributed; rather, they were strongly skewed to shorter reading time or fewer reading errors. In addition, they were significantly extended toward either longer reading time or more reading errors. Except in the non-word reading task, most subjects only made a few reading errors. Seven subjects (17.5%) showed at least one score that was more than 1.5 IQR (interquartile range) higher than the third quartile of that subject's eight scores on the four tasks. Assuming that those seven children are potentially dyslexic, at least 3.8% of second-graders (seven out of 182) are suspected to be suffering from dyslexia. Conclusion: It is likely that the prevalence of dyslexia in Japan is comparable to that in Europe and the US. To confirm this, a more comprehensive study on a larger scale should be implemented in the future.