Unlocking Second Language Novel Metaphor Processing: Behavioral and ERP Insights From First and Second-Language English Users

A growing literature uses event-related potentials (ERPs) to investigate novel metaphor processing as a window into creative processes like conceptual expansion. Modulations of the N400 generally indicate that while novel metaphors are initially processed as semantic anomalies, after a connection is found relating the concepts, they pattern more with literal sentences. Existing research largely focuses on monolinguals, but less is known about novel metaphor processing in bilinguals' second language (L2). Here, we combine robust single-trial ERPs and behavioral measures to investigate how L2 English users process full-sentence novel metaphors. We compare our results to a previous study with English monolinguals using the same experimental design to test three competing hypotheses: L2 conceptual expansion will be more effortful than, more efficient than, or similar to L1. Group differences suggest more effortful processing for L2 English users than monolinguals. Behaviorally, L2 users show more sentence evaluation errors than monolinguals, particularly for anomalous sentences. ERP results in L2 users reveal an N400 semantic anomaly effect at the sentence-final position, with no significant differences between metaphorical and literal or metaphorical and anomalous sentences. Monolinguals show a graded N400 effect, with significant differences between literal and anomalous as well as metaphorical and anomalous sentences. By comparing L2 users' results with monolingual English users and using naturalistic full-sentence structures, our findings contribute to the emergent literature on L2 novel metaphor processing and conceptual expansion while also unraveling the cognitive challenges associated with incremental processing and integration of L2 metaphorical sentences.