Neurocognitive Mechanisms of Tactile Synaesthetic Metaphors in Mandarin Chinese: An ERP Study

This study utilized event-related potentials (ERPs) to investigate the semantic integration and neurocognitive mechanisms underlying the processing of tactile synaesthetic metaphors, focusing on the N400 and Late Positive Component (LPC) as primary electrophysiological indices. In Experiment 1, three sentence types were compared: literal tactile sentences, strong synaesthetic metaphors (mapping tactile sources onto other sensory domains to form prototypical cross-modal associations), and weak synaesthetic metaphors (mapping tactile sources onto non-sensory abstract domains). Behavioral results indicated that weak synaesthetic metaphors were processed with the highest efficiency (fastest reaction times and highest accuracy), while literal sentences elicited the slowest responses (p < 0.001). Electrophysiologically, strong synaesthetic metaphors elicited enhanced P200 and LPC amplitudes, reflecting increased attentional allocation and deeper semantic integration characteristic of "synaesthetic" processing. Conversely, weak synaesthetic metaphors evoked larger N400 amplitudes, indicating greater semantic integration effort and more pronounced "metaphorical" properties. Experiment 2 examined the directionality of strong tactile metaphors, revealing that touch-to-audition mappings exhibited higher behavioral efficiency and greater neural accessibility than touch-to-vision mappings. Taken together, these findings demonstrate that synaesthetic metaphor comprehension is a dynamic process in which synaesthetic and metaphorical properties coexist. These results provide neurophysiological evidence for embodied cognition and cross-modal language processing, advancing our understanding of the psycholinguistic pathways underlying synaesthetic metaphors.