What psychological process is reflected in the FN400 event-related potential component?

During many recognition contexts, old items elicit a more positive event-related potentials (ERPs) than new items at mid-frontal electrodes about 300-500ms. The psychological processes that are reflected in is ERP component (i.e., the FN400) has been vigorously debated. Some argue that the FN400 reflects familiarity, whereas others argue that it reflects conceptual implicit memory. Three experiments contrasted these two hypotheses by presenting pre-experimentally familiar (i.e., name-brand) products and novel, off-brand products. In addition, some of the off-brand products were conceptually primed by the name-brand product to determine how FN400 amplitude would be affected by conceptually primed, but novel, products. The results provided mixed support for both theoretical views, and it is integrated with a broader theoretical framework to characterize the psychological processes captured by the FN400.