Intervention and amelioration effects in the acquisition of Spanish object relative clauses: the role of word order and DOM

Abstract

In this study we tested the comprehension of Subject Relative Clauses (SRCs) and Object Relative Clauses (ORCs) by Spanish monolingual children aged 4-6. Our results provide novel evidence that a subject-object asymmetry holds true also for Spanish: SRCs are easier than ORCs. Moreover, the test of different types of ORCs revealed that both overt Differential Object Marking (DOM) and word order properties (i.e. the subject position within the relative clause) constitute ameliorating factors in the comprehension of ORCs. Children proved to benefit more from word order than DOM-marking, with pre-verbal subjects bringing about higher accuracy rates than overt DOM. Moreover, these cues interact when occurring together: children’s comprehension decreases when ORCs with a pre-verbal subject also feature overt DOM. We additionally measured children’s knowledge of the grammar underlying DOM through an ad-hoc Sentence Repetition Task and found that DOM constitutes an ameliorating cue only with children who have acquired it. At the empirical level, we integrate these findings with the vast literature on children’s comprehension of relative clauses and advance a new descriptive generalisation of which grammatical properties characterise as ameliorating cues across languages. At the conceptual level, we interpret our results as evidence for both processing-oriented theories and grammar-based accounts to intervention locality. Whereas the interaction between DOM and word order suggests an effect of processing cost, the fact that cues need to be associated with an acquired grammatical representation inevitably tie amelioration effects to language-specific factors. We show that this apparent contrast is predicted if amelioration effects are regulated at the interface between the grammar and the performance system, and argue in favour of an interface interpretation in line with tout court minimalist criteria.