The Influence of Lexical Category, Translation Direction, and Language Proficiency on Translation Coactivation in Korean-English Bilinguals

Abstract

The long-term goal of this dissertation is to advance the theoretical understanding of bilingual lexical organization and processing beyond the current focus on nouns. Bilingual speakers often have two words for the same concept across their two languages (i.e., translation equivalents). It is well established that noun translations are coactivated during bilingual lexical processing and that this coactivation facilitates cross-language noun retrieval. However, it remains unclear whether verb translations also result in facilitative coactivation and whether the strength of translation coactivation differs across grammatical categories. Evidence from monolingual speakers has demonstrated robust noun-verb differences in lexical organization and retrieval, emphasizing the need to examine grammatical category differences in bilingual lexical processing. Furthermore, it remains unclear whether the strength of verb translation coactivation is asymmetrical across translation directions (forward: L1-to-L2 vs. backward: L2-to-L1) and how increasing L2 proficiency affects this asymmetry. To address these gaps, this dissertation (1) compared the strength of translation coactivation across nouns and verbs, (2) examined asymmetries in translation coactivation across forward and backward directions for each grammatical category, and (3) investigated whether the magnitude of this asymmetry differs between bilinguals with intermediate and high L2 proficiency. This dissertation consisted of three studies with adult Korean (L1) - English (L2) bilinguals and used a translation priming paradigm to investigate the strength of translation coactivation. Across studies, noun and verb translation coactivation was examined across translation directions (forward vs. backward) and L2 proficiency levels (intermediate vs. high) using picture naming and word reading tasks. We found facilitative effects of translation coactivation for both noun and verb retrieval. The strength of coactivation differed across grammatical categories, with stronger verb coactivation in picture naming and stronger noun coactivation in word reading. In addition, translation coactivation for both grammatical categories was consistently greater in the forward than in the backward direction. This asymmetry remained unchanged across bilinguals with intermediate and high L2 proficiency. Based on these findings, this dissertation proposes a revised Bilingual Integrated Grammatical Category (BIGC-R) model that accounts for grammatical category differences and L1-L2 asymmetries in translation coactivation, providing a comprehensive account of bilingual lexical organization across nouns and verbs and across languages.