Metaphorical and non-metaphorical links: a behavioral and ERP study in young and elderly adults

Event-related potentials (ERPs) and reaction times were recorded in a semantic decision task with isolated word pairs. The two words in each pair had either a metaphorical semantic link or a non-metaphorical semantic link. The metaphorical semantic link implied familiar expressions. Two conditions without any semantic link were also used, where the two words had a phonological relationship or not. Normal young adults and elderly people participated in this task. Subjects had to decide whether a target word presented 700 ms after a prime word was or was not semantically linked to the prime. Among word pairs with semantic relation, some pairs presented a metaphorical link, and the others presented a non-metaphorical link. Among word pairs without semantic relation, some pairs had a phonological relationship, and the others had no specific relationship. Familiar metaphorical expressions were used. In the two groups, target words elicited larger N400 components when they were related to the prime word by a metaphorical semantic link than when the semantic link was not metaphorical. No significant differences were found between the metaphorical semantic link condition and the two conditions without semantic link. The reaction times analysis showed that young and elderly people took more time to respond to the metaphorical semantic link than to the non-metaphorical semantic link. These results suggest that understanding metaphorical semantic links requires a lexical controlled process and that metaphors have a special status in the semantic memory.