Two Sites, Two Languages: Dual-site tDCS and EEG Evidence for L1 Feature Transfer in L2

Abstract The neural bases of syntactic and semantic processing remain unclear. While prior transcranial direct current stimulation (tDCS) studies have targeted either the inferior frontal gyrus (LIFG) or left superior temporal gyrus (LSTG), we test whether dual stimulation of both alters second language (L2) anomaly based on native language (L1). Chinese and Korean participants evaluated Japanese sentence correctness; Japanese shares morpho-syntax with Korean and semantic radicals with Chinese. For the N400, dual anodal tDCS elicited a significant interaction stimulation and L1 ( F (1,960.7) = 5.48, p = 0.0194), stimulation and sentence type ( F (5,960.7) = 2.28, p = .0448), and L1 and sentence type ( F (5, 960) = 2.28, p = 0.045). For the P600, a significant effect of stimulation and L1 interaction ( F (1,1303.1) = 9.86, p = 0.0017), and stimulation x sentence type ( F (5,1303.1) = 2.35, p = 0.039), suggesting L1 typology affected semantic integration during dual-stimulation tDCS.