Translation direction and word familiarity in word translation: an fNIRS study of intermediate Japanese learners of English.

Introduction: Many studies have examined the neural bases of word translation based on the revised hierarchical model (RHM). However, the findings reported thus far, mostly focusing on advanced or elementary second-language (L2) learners, have been diverse and often inconsistent. Thus, to explore possible neural bases for translation asymmetry, there is a distinct need to examine word translations by intermediate L2 learners. Methods: We examined differences in cortical activation patterns during L1 (first language)-to-L2 and L2-to-L1word translation for high and low word familiarity in intermediate-level Japanese learners of English. TOEIC scores were used to confirm intermediate English proficiency, and functional near-infrared spectroscopy (fNIRS) was used to examine cortical activation patterns during word translation. Data from 36 participants were used for analyses. Results: Greater activation was observed in the frontopolar area, the pars triangularis of Broca's area, and the bilateral dorsolateral prefrontal cortex for low-familiarity words regardless of translation direction. Discussion: These findings provide no clear evidence of translation asymmetry in intermediate L2 learners but suggest the possible involvement of concept mediation in both translation directions.