Unitization congruence moderates the effect of unitization on associative recognition: evidence from event-related potentials

Recently, a growing number of studies have shown that familiarity can promote associative recognition when more than two types of stimuli are combined into a single entity. However, it is not clear why the effect of unitization on associative recognition varies in the different studies. In this study, we examined whether the unitization congruence (UC) between original image pairs and rearranged ones affects associative recognition.Participants were asked to learn relevant and irrelevant picture pairs for the encoding phase, and they needed to distinguish intact pairs from rearranged pairs for the retrieval phase, while event-related potentials (ERPs) were recorded during the whole process.The results of the behavioral experiments showed that the performances of recognition (Prs: hits-false alarms) were higher under the relevant condition than under the irrelevant one for both UC conditions, although this effect was much larger under the inconsistent UC condition than under the consistent one. The ERP results also revealed that there were larger early old/new effect (FN400) and late left parietal old/new effect (LPC) under the relevant condition than under the irrelevant ones, irrespective of its consistency or inconsistency. However, these effects were more significant for inconsistent conditions.These results indicated that UC can moderate the effect of unitization on associative recognition by increasing familiarity and recollection and revealed the need to match the level of unitization of materials arrangements in future studies.