N400 can be elicited from different experimental paradigms. One such paradigm is the lexical decision task where letter-strings are presented in sequence and the subject’s task is to decide whether the stimulus presented is a word or a non-word. Within this framework the task involves a semantic priming paradigm, where some of the words were antonym-pairs. Semantic priming task has been one of the most extensively used ERP paradigms to study the effect of priming on N400 (Bentin, 1989; Ganis et al., 1996). The semantic priming effect refers to the faster reaction time to the related targets than to the unrelated targets in a lexical decision task (Meyer and Schvaneveldt, 1971). This effect can also be observed in ERP tasks. Further, there is parallel between the N400 amplitude observed for words in a lexical decision task and the N400 amplitude observed to words in sentences (Kutas and Federmeier, 2000; Kutas and Hillyard, 1984; Taylor, 1953). In the semantic priming paradigm, a word preceded by an unrelated word (unprimed condition) produces a larger N400 in comparison to a word preceded by a related word (primed condition) (McCarthy and Nobre, 1993).
