Effects of semantic distance and metaphorical constituent position on L2 noun-noun metaphor processing: an ERP study

The present study used event-related potentials to investigate the neural mechanisms underlying second language noun-noun metaphor (L2 NNM) comprehension, focusing on semantic distance and metaphorical constituent position. Forty Chinese English majors who had passed TEM-8 completed a 2 (semantic distance: large vs. small) × 2 (metaphorical constituent position: modifier vs. head) within-subjects experiment. English NNMs were presented alongside literal and nonsensical fillers in a metaphor (non)sense judgment task. Results revealed a biphasic N400-LPC pattern in NNM processing, indicating early semantic incongruity detection followed by meaning reanalysis. Both semantic distance and metaphorical constituent position exerted reliable main effects on ERP responses. Larger semantic distance (LSD) increased integration complexity and induced shallower semantic processing, while metaphorical modifiers (MM) triggered higher structural integration costs. Notably, only semantic distance exerted significant effect on late LPC, suggesting that L2 processing involves stronger semantic analysis but shallower structural analysis. In addition, the scalp distribution of these effects was right-lateralized, supporting the right-hemispheric view in metaphor resolution. No interaction effect was observed at early stage, suggesting that the two factors make largely independent contributions. However, significant interaction was observed on late posterior LPC. The effect of semantic distance was attenuated in MM constructions, and the effect of metaphorical constituent position was absent in LSD conditions, suggesting less elaborated processing due to the integration difficulties. Overall, these findings clarify the crucial roles of semantic distance and metaphorical constituent position in L2 NNM processing and offer pedagogical implications for L2 metaphor instruction.