Vowel categorization accuracy and its relationship to phonemic awareness

Cross-language speech perception studies regularly employ categorization tasks to determine listeners’ repertoire of phonological categories. In these tasks, participants select a phoneme from a list of letters or keywords to indicate which speech category they heard. However, recent studies have shown poor categorization accuracy when native (L1) English speakers are asked to categorize English vowels. Categorization tasks require phonemic awareness (PA), the explicit knowledge that words consist of segments, which is acquired alongside alphabetic literacy. Individual differences in PA may account for variability in L1 categorization accuracy. That is, participants with poor phonemic awareness may have difficulty explicitly identifying phonemes in a categorization task, particularly for English vowels, where grapheme-phoneme correspondences are relatively opaque. To test whether PA is related to categorization accuracy, 115 L1 English listeners completed an L1 vowel categorization task and three PA tasks: phoneme counting, deletion, and reversal. Strong correlations were observed between categorization accuracy and all three PA tasks, suggesting PA may account for a substantial proportion of individual variability in vowel categorization tasks. This finding questions the utility of the categorization task for determining listeners’ phonemic categories and has further implications for assessing second language speech categories.