The present paper addresses Korean EFL learners’ acquisition of psych-verb and unaccusative constructions from a processing point of view. Korean learners’ interlanguage psych-verb constructions and unaccusative constructions are marked by underpassivization and overpassivization, respectively. While both kinds of errors are observed in Korean learners’ data, the processing account of language acquisition predicts that learners will commit underpassivization errors more frequently than overpassivization errors because passivization requires more processing. In order to see if the acquisition of psych-verb and unaccusative constructions is affected by the processing complexity of passivization, the present study compared learners’ performance on psych-verb and unaccusative constructions. Ninety six university students performed a timed grammaticality judgment task on the two types of constructions. The comparison of the learner performances between psych-verb and unaccusative constructions revealed that the learners were more accurate with psych-verb constructions than with unaccusative constructions. The learners’ accuracy with psych-verb constructions increased faster than unaccusative constructions, with the increase of the overall proficiency. The findings suggest that while processibility might be a major issue for low-level learners, there are other factors such as L1 transfer that exert a pervasive influence on the acquisition of psych-verb and unaccusative constructions.

Korean psych verb constructions are divided into two different types: agentive psych verb constructions and stative psych verb constructions. A considerable amount of literature has been devoted to explaining the different case-marking patterns of the two constructions. Building on the HPSG feature regime, I propose two types of semantic relations, i.e. the act-relation for agentive psych verbs and the psych-relation for stative psych verbs. Such different semantic relations explain the different cases that the verbs’ objects are marked with. In addition, I show that the proposed analysis well explains scope interpretation, polysemy relations, and verb alternation of the two constructions.