Sandhi-based predictability of pitch accent facilitates word recognition in Kansai Japanese speakers

This study investigates the predictability effects of pitch accent on word recognition using the sandhi rule in Kansai Japanese (KJ). Native KJ speakers and native Tokyo Japanese (TJ) speakers (control group) saw images of four objects while hearing modifier + noun phrases and selected the corresponding image as quickly as possible. The word-initial tone of the noun's initial mora was predictable or unpredictable based on the tone of the preceding modifier's final mora in KJ but not in TJ. Experiment 1 found faster reaction times in the predictable conditions compared with the unpredictable conditions in KJ speakers but only when the modifier had an all-low tone sequence. This finding suggests that a modifier-ending that changes following the sandhi rule can function as a reliable cue to constrain an upcoming tone, whereas a modifier-ending tone that remains the same as in the citation form cannot (although the next tone is predictable). Unexpectedly, we found the same effect, albeit weaker, in TJ speakers. Experiment 2 replicated this effect and additionally showed that the facilitation effect was not due to TJ speakers having sufficient exposure to KJ to be familiar with the KJ sandhi rule. We speculate that the effect in TJ speakers is related to a language universal constraint against a sequence of low tones without a high tone within a phonological word, which may urge listeners to listen for a high tone in the upcoming input.