The Impact of Conversational Turn-Taking on Vocabulary Size in Toddlers With Developmental Delays Using Augmentative and Alternative Communication

Purpose: This study tracked the growth of conversational turn-taking during augmentative and alternative communication (AAC) intervention and evaluated how conversational turn-taking influenced the effectiveness of a 12-week augmented language intervention. Method: This study is a secondary analysis of archival data from Romski et al. (2010) and Romski et al. (2025). In total, 109 parents and their children with a variety of developmental delays (DDs) were randomly assigned to four intervention conditions across the two studies: (1) augmented input, (2) augmented output, (3) augmented input and output, and (4) spoken communication (SC). Language transcripts, including conversational turn count (CTC) and spontaneous augmented/spoken words, were transcribed using the Systematic Analysis of Language Transcripts software for 30-min interaction sessions between the parent and child at baseline, Session 18, and Session 24. Results: Total CTCs between parent–child dyads were found to have a quadratic growth curve. When separated by speaker, both parents and children had similar quadratic growth in CTCs over the course of the intervention. Additionally, it was found that exposure to AAC moderated the relationship between conversational turns and vocabulary size, such that higher rates of conversational turns were related to larger vocabulary size but only in parent–child dyads exposed to AAC conditions. Conclusions: AAC creates a unique communicative environment where children with DD can reap the benefits of increased CTC not seen in traditional SC interventions. Parents and practitioners can couple AAC intervention with encouragement of more conversational turns within the population.