Development of Multi-level Linguistic Alignment in Child-adult Conversations (2020)

Abstract: Interactive alignment is a major mechanism of linguistic coordination. Here we study the way this mechanism emerges in development across the lexical, syntactic, and conceptual levels. We leverage NLP tools to analyze a large-scale corpus of child-adult conversations between 2 and 5 years old. We found that, across development, children align consistently to adults above chance and that adults align consistently more to children than vice versa (even controlling for language production abilities). Besides these consistencies, we found a diversity of developmental trajectories across linguistic levels. These corpus-based findings provide strong support for an early onset of multi-level linguistic alignment in children and invites new experimental work.

## introduction linguistic alignment is the tendency that interlocutors have to change the way they talk to accommodate their conversational partners. this can happen through mirroring the partner's linguistic behavior on many levels such as the choice of words, syntactic structures, and semantic topics. linguistic alignment is considered an important mechanism for establishing common ground and rapport, fostering successful communicative interactions @xcite . in addition, understanding this coordination in its natural context is crucial for the design of conversational systems that interact with people in a natural and effective fashion @xcite @xcite . while alignment has been largely studied with adults @xcite @xcite @xcite , little has been done to investigate how it manifests in the context of childadult early communication and how it evolves across development. this is a significant gap in the literature. the child-adult early communication cannot be thought of as a simple extension of conversational dynamics between adults; it involves strong asymmetries in terms of cognitive abilities and social roles and, thus, requires more dedicated research @xcite . in addition, the study of child-caregiver linguistic interaction informs our theories of children's cognitive development. on the one hand, children's developing abilities in managing a conversation -through mechanisms such as interactive alignment -is a window into their emerging social-cognitive skills @xcite . on the other hand, the way caregivers use alignment across development allows us to understand whether and how adults tune their talk to children's developing cognitive abilities. such tuning has been suggested to play a pedagogical role, supporting linguistic and conceptual learning @xcite @xcite . ## analyses and discussion we model each type of alignment with a separate mixed-effects model, predicting alignment at a given linguistic level (lexical, syntactic, and conceptual) by age and alignment direction (adults aligning to children or vice versa). to take into account possibly correlated data from the same child, we used the identity of the child as a random effect. foot_1 for the binary processes (i.e., 0 vs. non-0 and 1 vs. non-1), the model was fit using binomial regressions. for the continuous process (i.e.,]0,1[), the model was fit using a linear regression. figures 1 and 2 show the results. ## conclusion and future work this study offered the first large-scale test to multilevel alignment in the context of natural child language. the results confirm some previous findings and uncover new ones. one question for future experimental work is whether such patterns can be produced in controlled behavioral experiments. finally, while we addressed english-speaking children's interactions, we plan to generalize this work cross-culturally in future investigations.