We report a syntactic priming experiment that examined whether children's acquisition of the passive is a staged process, with acquisition of constituent structure preceding acquisition of thematic role mappings. Six-year-olds and nine-year-olds described transitive actions after hearing active and passive prime descriptions involving the same or different thematic roles. Both groups showed a strong tendency to reuse in their own description the syntactic structure they had just heard, including well-formed passives after passive primes, irrespective of whether thematic roles were repeated between prime and target. However, following passive primes, six-year-olds but not nine-year-olds also produced reversed passives, with well-formed constituent structure but incorrect thematic role mappings. These results suggest that by six, children have mastered the constituent structure of the passive; however, they have not yet mastered the non-canonical thematic role mapping. By nine, children have mastered both the syntactic and thematic dimensions of this structure.
Messenger, K., Branigan, H. P., & McLean, J. F. (2011). Is children's acquisition of the passive a staged process? Evidence from six- and nine-year-olds' production of passives. Journal of Child Language, 39(5), 991-1016. https://doi.org/10.1017/S0305000911000377