The Developmental Trajectory of Nonadjacent Dependency Learning

We investigated the developmental trajectory of nonadjacent dependency learning in an artificial language. Infants were exposed to 1 of 2 artificial languages with utterances of the form [aXc or bXd] (Grammar 1) or [aXd or bXc] (Grammar 2). In both languages, the grammaticality of an utterance depended on the relation between the 1st and 3rd elements, whereas the intervening element varied freely. High variability of the middle element is known to contribute to perception of nonadjacent dependencies (Gómez, 2002), but the developmental trajectory of such learning is unknown. Experiment 1 replicated the study of Gómez with a younger age group and a more subtle variability manipulation. Twelve-month-olds failed to track nonadjacent dependencies under conditions tested here (Experiments 2a and 2b), but by 15 months, infants are beginning to track this structure (Experiment 3). Such learning has implications for understanding how infants might begin to acquire similar structure in natural language.