However, more recently, some have questioned the distinction between the N400 and FN400. Topographical differences (which are difficult to interpret given the possibility of component overlap) and paradigmatic differences notwithstanding, no study has actually dissociated the N400 from the FN400. Indeed, some evidence indicates functional similarity. For instance, like the N400, the FN400 does not vary in latency as a result of multiple encounters with the same stimulus (Johnson et al 1998). Moreover, Paller and colleagues (2007) have argued that empirical evidence showing the FN400 is not sensitive to conscious recollection does not necessarily warrant the conclusion that it must be related to familiarity.
