Metaphor processing is influenced by stimulus emotionality and task demands: Evidence from ERPs

Past studies showed that metaphoric expressions (e.g., "she was cold to him") require more cognitive-neural effort than literal paraphrases (e.g., "she was indifferent to him"). In event-related potentials (ERP) studies, this was revealed as an N400, a late positivity (LP), and/or a late negativity (LN). We investigated whether stimulus emotionality and task demands influence these ERP correlates and metaphor processing. In Experiment 1, participants read emotional/neutral metaphorical/literal sentences and performed a sensicality judgement task. Emotional metaphors, in comparison to emotional literal sentences, showed a widespread N400 effect (300-450 ms) and a left-anterior LN (450-850 ms). In Experiment 2, participants simply read the sentences and participation was verified by occasional post-trial comprehension questions. Emotional metaphors elicited a more positive LP (450-850 ms) than emotional literal sentences. Findings indicate that stimulus emotionality and task demand co-determine the extent to which emotion- and semantic- related neural resources are recruited during metaphor comprehension.