Speech Categorization Consistency Predicts Language and Reading Abilities in Korean School-Age Children

Purpose: Speech perception continues to develop throughout school age and plays a fundamental role in language and reading development. Recent findings in English-speaking children suggest that speech categorization consistency—the stability of a listener’s percept across multiple encounters with a speech sound—predicts both language and reading abilities, with a particularly strong link between reading skills and vowel perception. One hypothesis is that this is due to complex grapheme-phoneme correspondences (GPCs) in English vowels. The present study tested (1) whether the relationship between categorization consistency and language/reading abilities extends to typologically different languages and (2) whether the vowel-specific link observed in English is shaped by GPC complexity, using data from Korean, a language with relatively transparent GPC mappings.Method: Forty-four 1st-grade Korean-speaking children completed a Visual Analog Scaling (VAS) task, in which they heard tokens from a speech continuum and rated the correspondence between the stimulus and each word on a continuous scale. Standardized assessments of language and word reading were also conducted. Results: Children with poorer language/reading abilities exhibited lower categorization consistency, which is consistent with the findings from English-speaking children. In contrast to prior findings, however, this relationship was not specific to vowel perception but was held across all contrast types tested. Categorization gradiency (slope of the categorization function) was not significantly associated with any outcome. Conclusions: These findings extend prior work by demonstrating that categorization consistency predicts language and reading abilities, even in a language with transparent GPCs. Importantly, this association was observed across all phonemic contrasts, not just vowels—suggesting that the previously observed vowel-specific link in English may stem from the greater GPC complexity of English vowels. Together, while categorization consistency appears to be a critical predictor of linguistic outcome, the specific pattern may vary across languages depending on the structure of their GPCs.