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The Rule Learning of Phonological-Based Linguistic Categories: an fMRI Study
Poster B105 in Poster Session B, Tuesday, October 24, 3:30 - 5:15 pm CEST, Espace Vieux-Port
Diego Elisandro Dardon1, Chunlin Liu1, Motoaki Sugiura1, Hyeonjeong Jeong1; 1Tohoku University
Learning a second language requires the mastery of various grammatical rules, such as word order or nominal classification. Previous studies in grammatical rule learning have identified the left inferior frontal gyrus (IFG) and the adjacent motor area important for learning (Friederici & Opitz, 2003; Hauser et al., 2012). However, these studies focused on formal rules without semantic/phonological content, neglecting more typologically diverse rules that do integrate semantic/phonological information with formal patterns. This focus can lead to biased models of L2 learning while missing out on neurocognitive consequences of linguistic typology. In this study, we investigated the learning of sound-based nominal classification systems, grammatical rules that combine formal properties with phonological information to categorize the natural world. Since learning these rules is impossible without access to phonology to generalize correct categories, we predicted left IFG activation but novel activation in areas related to phonological processing particularly the left superior temporal gyrus and supplementary motor area (Nevat et al., 2017). Participants were 21 healthy, right-handed Japanese native speakers (Age 18-33, 10 females). We created a semi-artificial language with 72 concrete Japanese nouns divided into phonological categories commonly found typologically (Aikhenvald, 2000). The categories were divided according to a noun`s vowel ending (e.g., -a, -o, and -u). The target grammar rule was agreement between a noun`s ending and an agreeing demonstrative (e.g, sofa he; miso mi). Participants were scanned as they learned the semi-artificial language over 3 learning phases. During each learning phase, participants listened to 18 randomized correct noun-demonstrative combinations (learning condition) with each noun-demonstrative combination including a picture of the noun to prevent ambiguity. They heard the same 18 noun-demonstrative combinations but with the sound in reverse and a mosaic picture (control condition). After each learning phase, participants performed an offline grammatical judgment task, a behavioral indicator of learning. A paired-samples t-test was conducted on behavioral test scores between the first and last test phases. There was a statistically significant increase in scores between the first test (M = 11.33, SD = 3.82) and last test (M = 13.61, SD = 4.51), t (20) = -3.21, p = .004 (two-tailed) indicating learning took place over time. For the fMRI analysis, the contrast of interest was Learning Phase 1(- Control 1) vs Learning Phase 3(- Control 3) to find activation associated with learning as evidenced by the behavioral data. The statistical threshold for the voxel-wise analysis was p < 0.001 (uncorrected) for cluster formation and corrected to family-wise error (p < 0.05) using cluster size. fMRI analysis of the contrast Learning Phase 1(-Control 1) vs Learning Phase 3(-Control 3) revealed significant activation in the left STG. For the same contrast, activation in the left IFG was significant after small volume correction (p < .05). The findings indicate that both regions associated with formal rule learning and those associated with the underlying information categories are crucial for successfully learning linguistically diverse rules. These results significantly contribute to our understanding of the neurobiological mechanisms of L2 grammar acquisition, specifically in relation to linguistic typology.
Topic Areas: Language Development/Acquisition, Phonology