N400 modulations in metaphor evaluation and its associations with attentional systems: A behavioral and ERP study

Although metaphoric language is one of the most common expressions of creativity in everyday life, the neurocognitive mechanisms underlying conventional and novel metaphor processing are not fully understood. In particular, the role of attention in metaphor comprehension is lacking. The first aim of this study was to investigate the N400 event-related potential (ERP) component produced by conventional metaphor and novel metaphor evaluation. The second aim of this study was to explore the associations between attentional networks (alerting, orienting, and executive control) and the N400 amplitudes produced by conventional and novel metaphor evaluation. The participants performed a metaphor evaluation task, in which novel and conventional metaphors were presented, while ERPs were recorded. They were required to evaluate how novel is each sentence. In addition, a short version of the attention network test was administered to investigate three attention networks, alerting, orienting, and executive control. The behavioral results of the metaphor evaluation task showed that novel metaphors were rated slower and as more novel than conventional metaphors. The ERP parameters indicated that the N400 peaked earlier for conventional metaphors compared to the novel metaphors. In addition, novel metaphors produced larger amplitudes over the LH compared to those evoked by the conventional metaphors. Moreover, while conventional metaphor evaluation was not associated with the attentional networks, novel metaphor evaluation was associated with the executive control network. The findings suggest that novel metaphor evaluation is associated with different cognitive demands compared to conventional metaphor evaluation, and each of the metaphors differently interacts with attention