On recognizing Japanese Katakana words: explaining the reduced priming with Hiragana and mixed-Kana identity primes

The Japanese kana syllabary has 2 allographic forms, hiragana and katakana. As with other allographic variants like the uppercase and lowercase letters of the Roman alphabet, they show robust form-independent priming effects in the allograph match task (e.g., Kinoshita, Schubert, & Verdonschot, 2019), suggesting that they share abstract character-level representations. In direct contradiction, Perea, Nakayama, and Lupker (2017) argued that hiragana and katakana do not share character-level representations, based on their finding of reduced priming with identity prime containing a mix of hiragana and katakana (the mixed-kana prime) relative to the all-katakana identity prime in a lexical-decision task with loanword targets written in katakana. Here we sought to reconcile these seemingly contradictory claims, using mixed-kana, hiragana, and katakana primes in lexical decision. The mixed-kana prime and hiragana prime produced priming effects that are indistinguishable, and both were reduced in size relative to the priming effect produced by the katakana identity prime. Furthermore, this pattern was unchanged when the target was presented in hiragana. The findings are interpreted in terms of the assumption that the katakana format is specified in the orthographic representation of loanwords in Japanese readers. Implications of the account for the universality across writing systems is discussed.