The fact that one of the first variables found to clearly modulate N400 amplitude was repetition meant that the N400 could also be used to study aspects of recognition memory (reviewed in Friedman & Johnson 2000). N400 patterns in recognition tasks were similar to those seen for repetitions, with correctly identified old words eliciting less negativity in the N400 time window than correctly rejected new words. Dissociations of N400 memory-related effects from those on later components (such as the Late Positive Complex (LPC)) then helped to provide key support for multiple process/systems views of memory. Smith and Guster (1993), for example, provided early evidence for a dissociation between N400 memory effects and those due to recollection by showing that the magnitude of the N400 repetition effect was similar for memory judgments that entailed recollection or only a feeling of familiarity (whereas LPC modulations were yoked to recollection). The N400 also played a role in emerging studies using back-sorting paradigms to examine encoding-related brain activity that predicted later memory performance (a procedure later adopted by fMRI researchers, e.g., Jordan et al
