Contextual effects on conceptual blending in metaphors: An event-related potential study

Blending theory proposes that metaphor involves mappings between elements in two distinct domains and integration of information from these two domains. Previous event-related potential (ERP) studies have suggested that literal mapping occurs during metaphor comprehension. However, it has remained unclear whether accessing literal meanings affects metaphor comprehension and the contextual factors affecting blending remain poorly understood. The present study used a two stimulus word-to-sentence matching paradigm to study the effects of literal mapping and semantic congruity on metaphor comprehension using probe words from different domains. ERPs were recorded when 18 participants read short novel metaphors (e.g., The girl is a lemon) or literal control sentences (e.g., The fruit is a lemon) preceded by either a relevant or irrelevant word. Five conditions were measured: congruent target metaphor, congruent source metaphor, congruent literal, incongruent metaphor, and incongruent literal conditions. The analysis of the late positive components (LPC) revealed a significant difference in the P600 amplitudes between incongruent and congruent conditions. We also demonstrated that mapping across remote domains evoked larger P600 amplitudes than mapping across close domains or performing no mapping. The results suggest that the demands of conceptual reanalysis are associated with conceptual mapping and incongruity in both literal and metaphorical language, which supports the position of blending theory that there is a shared mechanism for both metaphoric and literal language comprehension. Amplitude differences suggest that integration difficulty is modulated by mapping degree rather than the timing of lexical access in the present study. Our results do not provide evidence that directly supports earlier models that propose literal meanings are accessed before or in parallel with metaphoric meanings.