In terms of SLA, Pornsiri Singhapreecha conducted a study on grammatical development of English Case, Tense, and Agreement features by Thai learners as her dissertation research, and has recently conducted a study (jointly with Juntarote) addressing a question of whether learners acquire the internal phrase structures, i.e. complements vs. adjuncts of their L2 in a way predicted by Universal Grammar.

With respect to syntax, her research has addressed a common underlying head-initial structure of Thai nominals and a functional status of Thai classifiers, a Thai linker thîi as a signal of Predicate Inversion (jointly with Marcel den Dikken), and the role of thîi as an infinitive marker (on a par with di in Italian, and de in French) and its connection with a hypothetical tense.

At the IIAS, she is conducting research with Professor Rint Sybesma (Department of Chinese Studies, Leiden University) on the topic of “Thai Split Nominals”. Thai quantified nominals are particularly interesting in that the numeral and the classifier (Nume-Cl) can be separated from the noun phrase that they are associated with by a predicative element. Research (cf. Yodkhamlue, 2004; Simpson, 2004) has proposed the split nominal phrase as a derived output of a single constituent. Singhapreecha and Sybesma have found the single constituent hypothesis to be problematic since it cannot account for the semantically associated part-whole relationship (i.e. partitivity). As an alternative, they propose the split approach and suggest that the NP and Nume-Cl are separate at the base, and the NP is established as a topic. They will continue to find answers to questions such as what exactly the syntactic position of the Nume-Cl is and how topic-hood is established in Thai relevant structures.