THE ACQUISITION OF ENGLISH RESTRICTIVE AND NON-RESTRICTIVE RELATIVE CLAUSES BY L1 THAI LEARNERS

Abstract

This study examined the acquisition of English restrictive and non-restrictive relative clauses (RRCs and NRRCs) by L1 Thai learners in order to test whether three RC-related hypotheses, namely the Noun Phrase Accessibility Hierarchy (NPAH), the Perceptual Difficulty Hypothesis (PDH), and the SO Hierarchy Hypothesis (SOHH), all of which had previously been confined to RRC data, would be equally applicable to NRRCs. As the distinction between English RRCs and NRRCs does not rely on the differences in linear syntactic arrangements that affect the factors these hypotheses are hinged upon, it was hypothesized that these three RC-related hypotheses would be equally applicable to both types of RCs. However, because NRRCs are less common, it was also hypothesized that the acquisition of NRRCs would diverge from that of RRCs. A sentence interpretation task and a grammaticality judgment task were administered to 40 undergraduate students (20 intermediate learners and 20 advanced learners) and five native speakers. The results showed that out of the three RC-related hypotheses, only the NPAH was the hypothesis that both RRC and NRRC acquisition trajectories appeared to conform to, lending support to previous works on L1 Thai learners and suggesting that the NPAH could be extended to NRRCs as well. The PDH seemed to apply only to the acquisition of RRCs while the acquisition of NRRCs systematically challenged the hypothesis, a phenomenon which was ascribed mainly to the possibility that NNRCs have a prototype different from that of RRCs. Interestingly, both RRC and NRRC data did not conform to the prediction made by the SOHH and suggested that discontinuities alone, as proposed by the hypothesis, could not adequately predict the acquisition orders for both RRCs and NRRCs. In addition, the results also demonstrated that learners experienced more difficulty in acquiring NRRCs than RRCs. This asymmetry in acquisition was attributed mainly to NRRCs’ rarity and lesser degree of prototypicality in comparison to RRCs, as well as transfer of instruction and overgeneralization.