Subject–verb agreement: Three experiments on Catalan.

This article investigates the ability of Catalan-speaking children and infants to parse subject–verb agreement, focusing on number agreement in third-person singular and plural forms within null-subject and overt subject sentences. Two picture selection experiments with children aged 3 to 6 showed that while younger children initially struggled with singular null-subject sentences, introducing numeral distractors improved their performance across all conditions. A third experiment using eye-tracking with infants around 19 to 22 months demonstrated that even at this early age, infants can parse subject–verb agreement in null-subject sentences. The findings suggest that difficulties observed in previous studies likely stem from task demands or pragmatic factors rather than from a delay in syntactic knowledge, supporting the view that children acquire the syntactic mechanisms for agreement comprehension early in development.