Letter visual similarity of Japanese hiragana and katakana based on reaction times

Hiroki Higuchi,Tessei Kobayashi

doi:10.1007/s12144-021-02664-w

Abstract

AbstractLetter similarity (i.e., perceptual distance) is a critical measure to better understand letter perception and literacy development. Despite its importance, however, measurements of letter similarity for non-alphabetic scripts are limited, and the shortage of letter similarity for non-alphabetic script interferes with the identification of the universality and the uniqueness of letter perception systems across different scripts. In the present study, we provide a comprehensive matrix of letter similarity for Japanese kana letters (hiragana and katakana). We obtained the discrimination reaction times for simultaneously presented letter pairs and calculated the perceptual distance of 4,278 letter pairs by inversing the time. The matrix showed significant correlations with previously obtained letter similarity for hiragana and katakana. An additional experiment showed that letter pairs for the same sounds (え–エ) produced significantly slower responses compared with those for different sounds (え–コ). However, the differences in reaction times between the same and different sound conditions were smaller than the sequentially presented conditions, suggesting that the matrix was partially attributable to knowledge-based factors (e.g., letter-sound knowledge). This first comprehensive matrix of letter similarity (i.e., perceptual distance) for Japanese kana letters (hiragana and katakana) will be useful for researchers interested in letter perception and literacy development.

Highlights

Letter perception is a critical step in reading because we cannot read any words without identifying the presented letters
Given these differences in writing systems, it might be fruitful to test whether cognitive models of letter perception and letter-knowledge development, which are established mainly based on studies of alphabetic scripts, are applicable to other language systems
Since the obtained data were converted to distance, similar letter pairs have small values

Summary

Introduction

Letter perception is a critical step in reading because we cannot read any words without identifying the presented letters. Letter similarity, which has been extensively measured in alphabetic scripts over the past 130 years, has contributed to studies that are theoretically building cognitive models of letter perception and reading as well as empirically investigating the development of reading related skills (see Mueller & Weidemann, 2012 for a review). A letter at the beginning of a sentence is capitalized in alphabetic script, this is not allowed in the Japanese kana writing system. Given these differences in writing systems, it might be fruitful to test whether cognitive models of letter perception and letter-knowledge development, which are established mainly based on studies of alphabetic scripts, are applicable to other language systems. Investigating similarity for Japanese kana (hiragana, katakana) letters is critical

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Discussion

Conclusion