The development of dependency length minimization in early child language: A case study of the dative alternation (2023)

Abstract: How does the preference for dependency length minimization (DLM) develop in early child language? This study takes up this question with the dative alternation in English as the test case. We built a large-scale dataset of dative constructions using transcripts of naturalistic child-parent interactions. Across different developmental stages of children, there appears to be a strong tendency for DLM. The tendency emerges between the age range of 12-18 months, slightly decreases until 30-36 months, then becomes more pronounced afterwards and approaches parents’ production preferences after 48 months. We further show the extent of DLM depends on how a given dative construction is realized: the tendency for shorter dependencies is much more pronounced in double object structures, whereas the prepositional object structures are associated with longer dependencies.

## introduction the principle of dependency length minimization (dlm) @xcite , originally developed based on the framework of dependency grammar @xcite , predicts that words or phrases that are syntactically dependent on each other prefer to appear closer in order to minimize the overall dependency distance, thereby reducing its structural complexity. while research on dlm thus far has been fruitful @xcite @xcite @xcite , one crucial question remains: how does the preference for shorter dependencies develop in early child language? given that the preference for dlm has been well-documented in the literature, we would expect to see similar preferences in child production as well. that said, it is unclear (1) at what developmental stage the preference for dlm emerges; (2) whether and how the extent of dlm varies along the developmental trajectory; (3) when children's production of dlm reaches a comparable level to that in parent/adult production. this study addresses the aforementioned questions using the dative construction in english as the test case. here (1a) and (1b) are different syntactic variants of the same dative construction: (1a) is a double object construction, (1b) is a prepositional object construction. within the verb phrase (vp) of (1a), the head verb has two noun phrase (np) dependents, one as the direct object (the toy) and one as the indirect object (me); the semantic roles for the two are theme and recipient, respectively. @xcite , the direct object dependent of the head verb, the toy, is the same as that in (1a), whereas the recipient is realized as a prepositional phrase (pp) dependent instead. leveraging transcripts of naturalistic childparent interactions and computational techniques, we analyze the developmental patterns of dlm in child production of the dative alternation. we foresee two possible directions regarding the extent of dlm across children's developmental stages. on one hand, at earlier stages, utterances produced by children are comparatively shorter @xcite ; based on evidence from written data that there is a positive correlation between overall dependency length and sentence length @xcite , this means that during these stages the preference for dlm is potentially weaker, and would gradually increase as utterance lengths increase when children reach later developmental stages. on the other hand, if the primary motivation for dlm is to lessen cognitive load @xcite @xcite , then at earlier developmental stages, when children have shorter working memory @xcite , they may have a stronger preference for shorter dependencies than they do in later stages of development. ## related work the dative alternation in english @xcite , has been studied extensively, specially in first language adult production @xcite @xcite . in addition, a number of studies have looked into the production patterns of the dative constructions in child (and child-directed) spoken language in english, though from different angles. one line of work probes the generalization @xcite @xcite and learnability @xcite of the dative structures in children's production. others attended to the developmental order of the different variants of the dative construction @xcite . with syntactic orders in particular, de @xcite investigated what structural constraints, such as animacy and pronominality, affect children's syntactic choices. ## discussion this study analyzed the developmental trajectory of the preference for dlm in child production using the dative alternation in english as the test case. our findings illustrated that the tendency for shorter dependencies emerges in child production during the age range of 12-18 months. the extent of the tendency decreases until 30-36 months, then gradually increases and approximates the production level in parent data around 42-48 months. in this work, we used age as the index of children's developmental stages. for future experiments, we plan to investigate how other alternatives, such as the mean length of utterance, affect observations of children's developmental trajectories of dlm. we would also like to analyze the development of children's syntactic choices via enriching the dataset with annotations for other constraints such as verb semantics. these factors could potentially provide additional explanations for the varying extents of dlm in children's early development. lastly, given that our dative dataset is much larger than prior ones, we hope that it will be useful to research topics related to acquisition of syntactic alternations more broadly.