Background:
Inequalities in early language exposure, known as the ‘word gap’, have been shown to emerge as early as 18 months old. Parent-child interactions, also known as conversational turns, have been proposed as one mechanism for improving later language development. However, research to date has been limited by small sample sizes and analytical techniques that cannot quantify a causal relationship, limiting the potential for research to inform policy and practice within early childhood.

Objective:
Estimate the causal effect of parent-child interactions throughout the early years on children’s later language development at 3 and 4 years old.

Methods:
Language in Little Ones is an Australian prospective cohort study (n = 302) that uses speech recognition technology to quantify the number of parent-child interactions children experience over an average day. Data is collected every six months from when the child is 6 to 48 months old. Language development is measured using the standard score on the Clinical Evaluations of Language Fundamentals Preschool-2 at 36 and 48 months. Marginal structural models with inverse probability of treatment weights will be employed to account for time-varying exposures (parent-child interactions) and time-varying confounding (e.g., home activities and parent mental health).

Results:
Using the counterfactual theory of causation, results of a simulation model will be presented that describes the language development standard score that could be expected had the entire population spoken a specified number of parent-child interactions at each wave of data collection.

Conclusion:
These findings will advance our understanding of how increases in parent-child interactions could improve language development during the early years. Potential mechanisms influencing parents’ ability to engage in high-quality interactions, such as screen time, will also be discussed. This will inform international policies and interventions to close the word gap and ensure all children start school ready to learn.