Perceptual fluency affects recognition memory under deep encoding conditions promoting recollection: Evidence from an ERP study using letter-segregated method.

Perceptual fluency can increase familiarity of some of the items in recognition tests and enhance attributions of these items to the past. It is not clear, however, whether perceptual fluency can influence recognition under conditions promoting recollection-based memory. To this end, we performed a systematic replication of a study by Lucas and Paller (2013) using a letter-segregated method. We recorded ERPs while participants performed recognition task in letter segregated (LS) blocks, in which new words were always composed of different letters than old words, and in letter non-segregated (LNS) blocks, in which half of the new words came from the same letter pool as the studied words (new related words), and the other half came from the other pool (new unrelated words). Unlike the Lucas and Paller study, deep encoding promoted more recollection-based memory. In the LNS blocks, the comparison between old and new unrelated words revealed early (180-260 ms) P200 old/new effect, showing that recognition can be supported by an early discrimination of perceptual differences between studied and unstudied test probes. The relatively large hit rates and relatively high sensitivity measures, as well as the late (500-700 ms) LPC old/new effects in both blocks, indicated high levels of recollection for old words. Still, recognition memory was more accurate in the LS blocks, whereas in the LNS blocks there were more false alarms for new related than for new unrelated words. This suggests that perceptual fluency derived from low-level information may influence not only familiarity, but also recollection-based memory judgments.