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The complementary systems for foreign language vocabulary learning: the impact of cognateness and ageing
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Xavreila Sheung-Wa Ng1, Cloris Pui-Hang Li1, Ashley Cheuk-Ying Cheung1, Fangfei Li1, Matthew King-Hang Ma1, Manson Cheuk-Man Fong1; 1The Hong Kong Polytechnic University
Previous fMRI studies on foreign language learning (FLL) indicate that the neural processes in vocabulary learning are strongly modulated by cognateness. Whereas learning cognates involves rapidly mapping onto pre-existing native lexical representations via Broca’s area, acquisition of noncognates often demands extensive cognitive control. However, these studies often focused not on the active learning process per se but the retrieval process after word acquisition. Another unknown lies in how the learning process differs across young and older adults. The complementary learning systems (CLS) theory provides a theoretical framework for predicting the neural dynamics underlying FLL. According to this theory, memory formation entails a dynamic progression immediate hippocampal encoding to long-term neocortical consolidation. Correspondingly, we hypothesised that (H1) the hippocampus is more engaged upon encountering non-cognates and unconsolidated words than cognates and consolidated words, while the opposite is true at the IFG due to the presence of long-term representations. We also speculated that (H2) such effects are especially prominent in younger adults, possibly due to the more effective acquisition of phonological rules; and (H3) within older adults, compensatory hyperactivation might be observed in MTL/hippocampus and Broca’s area. In addition, cognitive control regions and other core language areas (e.g., pSTG) were also included as regions of interest. 26 healthy older learners (aged 59–70) and 25 young learners (aged 19–30), all Hong Kong Cantonese–English late bilinguals, took part in a 3-month computerised Italian learning programme. The present analysis focused on an early-stage in-scanner active vocabulary learning/revision task, conducted after the participants finished the first vocabulary lesson. The task comprised 60 trials, each sequentially presenting a written Cantonese word, the corresponding written Italian word, and two successive auditory presentations of the Italian word. Word stimuli followed a 2×2 factor design crossing Cognateness (cognate/noncognate) and Consolidatedness (consolidated/unconsolidated), with consolidated words being words that had already been studied. All 60 trials were repeated once in a second run. FMRI data were acquired on Siemens 3T Prisma scanner (TR = 800 ms, voxel size = 2×2×2 mm³). Cortical and hippocampal ROIs were chosen based on HCP-extended and Julich atlas, respectively. Data preprocessing and functional activation analysis were conducted using Nipype and FSL, focussing on the first auditory presentation. Consistent with H1, while cognates elicited larger activation at IFG, the opposite was true at the left hippocampus subiculum, FDR-ps < .05; moreover, control regions such as left ventral and dorsal area 24d also showed the former pattern. The Consolidatedness effect was generally weaker, showing a trend for unconsolidated words to be more activated only at core language/semantics areas such as Left lateral inferior frontal gyrus, uncorrected-p = .001, FDR-p = .126. However, H2 was not supported as no significant interaction was found between AgeGroup and any of the two factors. Finally, consistent with the compensatory account (H3), older adults exhibited a more positive-going activation for the majority of ROIs. Overall, our results provide partial support for applying the CLS account in understanding foreign language vocabulary learning, and revealed widespread compensatory activities in older adults during active foreign vocabulary learning.
Topic Areas: Multilingualism,