Is KO OK? Segmentation of consonant- and vowel-initial words in German-learning infants

Infants develop the ability to segment words from continuous speech from the age of 6 months onwards. However, in French- and English-learning infants, this ability initially appears to be restricted to consonant-initial words. Vowel-initial word segmentation only emerges at around 13.5 months of age, or at 11 months when additional segmentation cues are provided. Previous research has attributed this asymmetry to phonological and acoustic differences between word-initial consonants and vowels. The present study examined whether distributional properties such as the likelihood of encountering vowel-initial words also contribute to this developmental pattern. For this, 114 infants learning German, a language with a higher proportion of vowel-initial words than English and French, were tested. Using the head-turn preference procedure, 11-month-olds (Experiment 1) and 8-month-olds (Experiment 2) were familiarized with isolated words beginning with either consonants or vowels. Subsequently, their preference for listening to text passages containing these words was assessed. While the 8-month-olds showed no evidence of segmentation for either word type, the 11-month-olds successfully segmented both consonant- and vowel-initial words, showing no advantage for either of the word types. The results support an input-based account: experience with a language richer in vowel-initial words may facilitate earlier segmentation of vowel-initial forms. Overall, the findings highlight the influence of language-specific distributional properties on early segmentation biases and underscore the need for research with infants learning structurally diverse languages.