Logographic Kanji versus phonographic Kana in literacy acquisition: how important are visual and phonological skills?

It is well-established that phonological skills are important for literacy acquisition in all scripts. However, the role of visual skills is less well understood. For logographic scripts in which a symbol represents a whole word or a meaningful unit, the importance of visual memory in literacy acquisition might be expected to be high because of the visual complexity of logographic characters, but in fact its role remains poorly understood. The Japanese writing system uses both phonographic "Kana" and logographic "Kanji" scripts concurrently and thus allows for the assessment of the contribution of phonological and visual processing to literacy acquisition in these two different scripts in the same language. We tested 74 Japanese children (39 second graders and 35 fourth graders) on a range of literacy, sensory, and cognitive tasks. We found that Kana literacy performance was significantly predicted by low-level sensory processing (both auditory frequency modulation sensitivity and visual motion sensitivity) as well as phonological awareness, but not by visual memory. This result is largely consistent with previous studies in other phonographic scripts such as English. In contrast, Kanji literacy performance was strongly predicted by visual memory (particularly visual long-term memory), but not by either low-level sensory processing or phonological awareness. Our results show differences in the skills that predict literacy performance in phonographic Kana and logographic Kanji, as well as providing experimental evidence that visual memory is important when learning Kanji. Therefore, children's literacy problems and remediation programs should be considered in the context of the script in which children are learning to read and write.