Effective When Distinctive: The Role of Phonetic Similarity in Nested Dependency Learning Across Preschool Years

Abstract Parallel tracking of distant relations between speech elements, so‐called nonadjacent dependencies (NADs), is crucial in language development but computationally demanding and acquired only in late preschool years. As processing of single NADs is facilitated when dependent elements are perceptually similar, we investigated how phonetic similarity affects parallel dependency processing in preschoolers (2–4 years old, N = 54). In a passive‐listening electrophysiology study, children heard syllable sequences with nested dependencies of the form [A 1 [A 2 C B 2 ] B 1 ], with A i predicting B i . Across sequences, either the inner, the outer, or both NADs were phonetically similar. Additional deviant sequences violated the dependencies by exchanging the last two syllables. Independent of age, children showed electrophysiological mismatch responses to dependency violations, but only when either outer or inner NADs were phonetically marked. This suggests that phonetic similarity can aid preschoolers in parallel dependency processing, but only if marking is distinctive in the linguistic structure.