Event‐Related Potentials in Chronometric Analysis of Primed Word Recognition with Different Stimulus Onset Asynchronies

In a lexical decision experiment in which primes preceded associatively related words, unrelated words, or non‐words, N1(154 ms)‐P2(245 ms), P2, and P3 (502 ms) increased in amplitude with increasing semantic association, while N2 (340 ms) amplitude, as well as response times, showed an opposite relationship and increased with decreasing semantic association. The relationship, in each case, persisted across a range of stimulus onset asynchronies (SOAs: onset‐to‐onset) from 1000 down to 200 ms. Despite the apparent dissociation of P2 and N2, it could not be unequivocally established that they reflected successive discrete phases of processing. The balance of evidence indicated that the variation of both P2 and N2 across conditions could be attributed to a widely distributed, slow negative process, which began on the N1‐P2 deflection, peaked at N2, and terminated beyond P3, and was enhanced when an automatically generated expectancy of a semantically associated word was violated. It is suggested that the negativity reflects an automatically generated enhancement of arousal that facilitates conscious processing of unexpected stimuli.