UCLA

Recent research has shown that 6-month-olds relate novel words suffixed with -s like babs and teeps that are embedded in passages, with just the stem bab and teep, demonstrating an early sensitivity to morphological relatedness. This study explores the limits of early morphological decomposition and its interaction with phonotactics. In two experiments, we evaluated whether monolingual English-learning 6-month-olds are sensitive to phonotactic well-formedness when detecting morphological relatedness. In Experiment 1, we tested infants on two different allomorphs of the English -s suffix: [-s] and [-z]. Then, in Experiment 2, we investigated whether infants decompose two different kinds of CV[z] sequences - one type where decomposition leads to stems with permissible sequences in English and another that creates stems with sequences that are not permissible. Our results indicate several important findings. Firstly, infants possess detailed allomorph-specific representations early in language development with the frequency of different allomorphs influencing early morpheme decomposition. Infants show sensitivity to the more common [-z] allomorph but not the less common [-s] allomorph. Secondly, early morpheme decomposition is not mandatory; infants do not segment every sequence containing a morpheme. Finally, phonotactic cues, even in the absence of semantic or distributional ones, play a crucial role in infants' morphological learning processes. These experiments highlight the interaction between phonotactic sensitivity and morphological acquisition from the earliest stages of language development.