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Disentangling Semantic Retrieval and Composition in Understanding "Novel-But-Familiar" Combinations
Poster Session B, Friday, October 25, 10:00 - 11:30 am, Great Hall 3 and 4
Ziyi Ding1, Ming Song1, Qing Cai1,2; 1Key Laboratory of Brain Functional Genomics (MOE & STCSM), Affiliated Mental Health Center (ECNU), Institute of Brain and Education Innovation, School of Psychology and Cognitive Science, East China Normal University, No. 3663, North Zhongshan Road, Shanghai, China, 200062, 2NYU-ECNU Institute of Brain and Cognitive Science, New York University Shanghai, No. 3663, North Zhongshan Road, Shanghai, China, 200062
Deriving combinatorial semantics from component words encompasses multiple processes, including the retrieval of known meanings and their integration into a unified entity. Previous research showed that the anterior temporal lobe (ATL) typically plays an important role in semantic composition. However, its activation is seldom observed in processing weak associations or unfamiliar combinations. Conversely, the middle temporal gyrus (MTG) predominantly responds to more challenging semantic combinations. The distinct functions of the ATL and MTG in semantic composition remain to be clearly defined. This study hypothesizes that the ATL primarily retrieves meanings for both individual words and their combinations as a whole, particularly for familiar combinations. In contrast, the MTG is crucial for the semantic composition of expressions, especially when the overall meaning is challenging to discern. We propose that both the ATL and MTG are integrally involved in combinatorial semantics. To further delineate the roles of composition and retrieval, this study includes a newly introduced condition termed "novel-but-familiar" combinations, which pairs familiar concepts with new expressions (e.g., ‘voice box’ for ‘stereo’). Participants were asked to make sense of these combinations during fMRI scans. Four types of combinations were included: familiar, novel, novel-but-familiar, and non-sensical. Each condition included 30 unique combinations. Each combination was presented twice, allowing comparisons between initial exposures and subsequent repetitions. We also minimized the syntactic effect by including an equal number of noun-noun and verb-object combinations. Combination types were reassigned based on responses from post-scanning questionnaires. To disentangle the roles of composition and retrieval, the current study introduced a new condition, "novel-but-familiar" combinations, which describe familiar concepts in novel expressions (e.g. "voice box (声音盒子)" corresponds to "stereo (音响)"). Participants were asked to try to comprehend the meanings of the combinations and decide their meaningfulness during fMRI scanning. Four types of combinations were randomly presented: familiar combinations, novel combinations, novel-but-familiar combinations, and nonsense combinations. Each type included 30 unique combinations, with each combination presented twice. An equal number of noun-noun and verb-object combinations was included to balance the impact of syntax. The types of combinations were reassigned based on the post-scanning questionnaires. Results showed that in line with previous findings, the ATL predominantly responded to familiar combinations, whereas the MTG was more active with novel combinations. Notably, the "novel-but-familiar" condition significantly engaged both the ATL (compared to "novel") and MTG (compared to "familiar"), suggesting their distinct roles in deriving combinatorial semantics. Finally, both the ATL and MTG exhibited significant activation in response to the first presentations compared to their repetition for all meaningful combinations. The results emphasize the collaborative efforts of the ATL and MTG in comprehending a wide array of conceptual combinations, suggesting that while the ATL underlies the retrieval of established meanings, while the MTG is actively involved in the composition of component meanings, especially for novel combinations that lack an integrated semantic representation.
Topic Areas: Syntax and Combinatorial Semantics, Meaning: Lexical Semantics