The role of semantic processing in reading Japanese orthographies: an investigation using a script-switch paradigm

Research on Japanese reading has generally indicated that processing of the logographic script Kanji primarily involves whole-word lexical processing and follows a semantics-to-phonology route, while the two phonological scripts Hiragana and Katakana (collectively called Kana) are processed via a sub-lexical route, and more in a phonology-to-semantics manner. Therefore, switching between the two scripts often involves switching between two reading processes, which results in a delayed response for the second script (a script switch cost). In the present study, participants responded to pairs of words that were written either in the same orthography (within-script), or in two different Japanese orthographies (cross-script), switching either between Kanji and Hiragana, or between Katakana and Hiragana. They were asked to read the words aloud (Experiments 1 and 3) and to make a semantic decision about them (Experiments 2 and 4). In contrast to initial predictions, a clear switch cost was observed when participants switched between the two Kana scripts, while script switch costs were less consistent when participants switched between Kanji and Hiragana. This indicates that there are distinct processes involved in reading of the two types of Kana, where Hiragana reading appears to bear some similarities to Kanji processing. This suggests that the role of semantic processing in Hiragana (but not Katakana) reading is more prominent than previously thought and thus, Hiragana is not likely to be processed strictly phonologically.