Gradual Route to Productivity: Evidence from Turkish Morphological Causatives

Abstract

Children’s spontaneous speech may not reflect true productivity with grammar rules. We investigated Turkish-learning children’s rule-based understanding of causative morphology by combining experimental and corpus work. We asked (1) when the generalization of causative morphology emerges and (2) what role input plays in this development. To answer the first question, Study 1 experimentally tested 106 children aged 2;6–6;1 on a language judgment task using pseudo-verbs. Children preferred the causative marker -DIr over an incongruent suffix for causativized events earliest at age 4;10. Further, Study 2 tested 38 children aged 3;6–4;6 and revealed no preference of -DIr over no suffix. Study 3 examined a corpus for child-directed input and showed that the variation of verb stems to which -DIr was attached remained lower than variation of verbs eligible to take -DIr, up to age 3. The findings suggest that rule-based understanding of morphological causatives emerges much later than previously proposed productivity at age 2, which might be accounted for by the insufficient variation of morphological causatives in the early input.

Do typological differences in the expression of causality influence preschool children’s causal event construal?

“…Given that there are both lexical and morphological causatives in Turkish, and that the morphological marker is not systematically present in every causal construction, the adult-like abstraction of the morphological marker may take more than three to four years. In fact, in another recent study, we showed that Turkish children reliably judged the use of the causative marker -DIr for causativized events only at the age of five (Ger, You, et al, 2021). Therefore, some children might have not yet acquired an abstraction for the causative marker and thus perceived the causatively marked pseudo-verb as an unmarked root verb.…”