The LPC is also sensitive to decision accuracy. It is larger in response to correctly identified old words than it is to incorrectly identified old words. For example, Finnigan and colleagues (2002) extended the traditional old/new effect paradigm by presenting new unstudied words and old words which had been presented at study either once ("weak") or three times ("strong"). The probability of an "old" response was significantly higher for strong than weak words and significantly higher for weak than new words. Comparisons were made initially between ERPs to new, weak and strong words, and subsequently between ERPs associated with six strength-by-response conditions. Results showed the amplitude of LPC effect was sensitive to decision accuracy (and perhaps confidence). Its amplitude was larger in ERPs evoked by words attracting correct versus incorrect recognition decisions. The LPC effect had a left > right, centro-parietal scalp distribution (in ear-referenced ERPs). Therefore, in addition to the majority of studies in which interpreted LPC from the perspective of dual-process models (which dissociate familiarity and recollection), Finningan et al. (2002) provided alternative interpretations of LPC in terms of memory strength and decisional factors.
