Proceedings of the Annual Meeting of the Cognitive Science Society

The acquisition of second language morphosyntactic features, such as case systems, is particularly challenging for adult learners, and the extent to which these difficulties are shaped by learners' first language remains a core question in theories of language acquisition. The present study explores the acquisition of lexical semantics and morphosyntax of a case-marking artificial language, Katopu, in an artificial language learning task with Korean-speaking and English-speaking adults. The results showed that both groups were able to acquire Katopu through the exposure to input and feedback, regardless of L1–L2 (dis)similarities and in the absence of explicit instruction, exhibiting comparable learning trajectories in accuracy and response time. Response time data further suggested that the two groups shared a similar processing pattern that semantic and syntactic knowledge were processed using separate mechanisms. The study highlights that sufficient input and feedback can effectively support language acquisition regardless of learners' language background.