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It is widely accepted that associative recognition can be supported by familiarity through integrating more than two stimuli into a unit, but there are still three unsolved questions: (1) how unitization affects recollection-based associative recognition; (2) whether it is necessary to match the level of unitization (LOU) between original and rearranged pairs, which was term as unitization-congruence (UC); (3) whether unitization can occur at encoding or at retrieval. The purposes of this study are to try to answer these questions. During the encoding phase, the participants were asked to learn compound words and unrelated word pairs, and during the retrieval phase, they needed to distinguish intact pairs from rearranged consistent and rearranged inconsistent pairs with "remember/know" paradigm. The results showed that (1) the role of unitization in recollection was moderated by UC; (2) Under the consistent UC condition, unitization could improve familiarity-based associative recognition without affecting recollection-based associative recognition, while under the inconsistent UC condition, unitization could improve familiarity-based and recollection-based associative recognition simultaneously, these results indicated that it was necessary to match the LOU between original and rearranged pairs; (3) unitization at encoding could support familiarity-based associative recognition, while unitization at retrieval did not. In briefly, unitization at encoding could improve associative recognition and this effect was moderated by UC, while unitization at retrieval did not affect associative recognition.

Previous research has suggested that familiarity can enhance associative memory after unitization, but the cognitive mechanisms underlying unitization remain debated. To explore the neural mechanisms of associative memory after unitization in the absence of semantic relations, we used Chinese characters as stimuli and recorded participants' blood oxygen level‐dependent signals during recognition. Behavioral results showed that after Chinese character unitization, not only the associative performance of recognition (Pr, hit rate minus false alarm rate) and general Pr but also the hit rate and correct rejection rate increased. Neuroimaging results revealed activation of the hippocampus and parahippocampal gyrus during associative recognition in both the unitized and the non‐unitized condition, and hippocampal activation increased after unitization. However, activation of the perirhinal cortex was not observed in either condition. These findings, in contrast to those from previous studies on unitization, suggest that Chinese character unitization enhances recollection‐based, rather than familiarity‐based, associative recognition. This suggests that the encoding of semantic relations during unitization is critical for subsequent familiarity‐based associative recognition. [ABSTRACT FROM AUTHOR]

Although it is widely accepted that familiarity could support associative recognition when the to‐be‐learn items are 'unitized' into a new representation, the effects of unitization on associative recognition and recollection remain much debated. The current study aimed to explain these debates by exploring when and how unitization benefits associative recognition using event‐related potentials (ERPs). During the encoding phase, participants learned compound words and unrelated word pairs (i.e., High vs. Low level of unitization). At retrieval, the compound words were rearranged into new compound words (i.e., no‐change) and unrelated word pairs (i.e., change). Similarly, the unrelated word pairs were rearranged into new unrelated word pairs (i.e., no‐change) and compound words (i.e., change). Results showed that under the no‐change condition, unitization did not affect associative recognition, nor its underlying processes. In contrast, under the change condition, unitization improved associative recognition by increasing both familiarity‐related FN400 effect and recollection‐related LPC effect. In addition, a planned comparison between the compound‐change and unrelated‐no change conditions—a common index for unitization effect in past studies—revealed that unitization could not only elicit significant FN400 effect, but also improve associative recognition by increasing LPC effect. Collectively, these results not only allowed to explain the current discrepancies in the literature concerning the effect of unitization on associative recognition, but also emphasized the importance of matching the level of unitization between the studied and rearranged word pairs. Although most studies have suggested enhanced familiarity‐based associative recognition when the to‐be‐learned items are unitized, the effects of unitization on associative recognition and recollection remain controversial. The current study aims to explain this controversy by manipulating the level of unitization within word pairs, both at encoding and when rearranged. Collectively, results could not only explain current discrepancies in the literature, but also emphasize the importance of matching the level of unitization between the studied and rearranged word pairs. [ABSTRACT FROM AUTHOR]

It is widely accepted that unitization can promote familiarity-based associative recognition, but the effect of unitization on item recognition remains unclear. The goals of this study were to elaborate on how unitization affected item recognition and the neural correlates of familiarity and recollection for item recognition. In study, the participants were asked to learn related and unrelated picture pairs, and in test, they were required to distinguish single old pictures form new pictures. In experiment 1, we used R/K/N paradigm to estimate the contribution of familiarity and recollection to item recognition, the results showed that unitization could improve item recognition through increasing recollection selectively. In experiment 2, we used ERP old/new effects to estimate the neural correlates of familiarity and recollection, the results showed that unitization could improve item recognition through a selective reduction in LPC effect. Inspired by DRM paradigm, in experiment 3, we divided the new pictures into semantically related lure pictures and semantically unrelated new pictures to explore the effects of unitization on item recognition and verbatim recognition (the ability to distinguish old pictures from lure pictures). The behavioral results showed that unitization could improve item recognition, but it damaged verbatim recognition. The ERP results revealed that there were larger LPC effects in the unrelated condition than in the related condition, regardless of item or verbatim recognition. In summary, we believed that unitization could indeed improve item recognition, but it damaged verbatim recognition. [ABSTRACT FROM AUTHOR]

It is widely accepted that associative recognition can be supported by familiarity through integrating more than two stimuli into a unit, but the role of unitization in recollection-based associative recognition remains unclear. In this study, we aimed to illustrate how the level of unitization (LOU) affected recollection-based associative recognition and to examine whether the unitization–congruence between original and rearranged picture pairs (UC) could have effect on the relationship between LOU and associative recognition. In encoding, participants were asked to learn related and unrelated picture pairs, and in retrieval, they needed to distinguish intact pairs from rearranged pairs. We also distinguished the LOU of the pairs based on its status at encoding or retrieval separately. The results showed that: (1) LOU-at-encoding could improve associative recognition through increasing recollection-based associative recognition selectively; (2) LOU-at-retrieval could improve associative recognition through increasing familiarity-based and recollection-based associative recognitions; (3) UC did not moderate the relationship between LOU and associative recognition. Hence, in future studies, researchers do not need to pay much attention to the construction of rearranged pairs to ensure that the LOU between original and rearranged picture pairs is matched. It greatly reduces the difficulty of materials selection. [ABSTRACT FROM AUTHOR]

• Unitization does not impede overall item recognition performance. • Unitization can maintain item recognition through less overall neural processing. • Both neural correlates of familiarity and recollection contributed to item recognition. • We use Bayesian analysis to explain the null results to ensure the reliability of the results. It is widely accepted that unitization can promote familiarity-based associative recognition, but the role of unitization in recognition of individual component elements which originate from compound words remains unclear. The goals of this study were to elaborate on how unitization affects item recognition and further examine the effect of unitization on the extent to which familiarity and recollection contribute to item recognition. During the study phase, participants were asked to learn 48 compound words and 48 unrelated word pairs, and during the test phase, they were instructed to distinguish old from new words. We disassociated the contribution of familiarity and recollection to recognition with remember/know paradigm in experiment 1 and with ERPs old/new effects in experiment 2. The results showed that the overall item recognition was equivalent between the two retrieval conditions. Disassociation the contribution of familiarity and recollection, we found that there was higher recollection-based item recognition performance for compound-old words than for unrelated-old words in experiment 1. In contrast, in experiment 2, the magnitude of later parietal old/new effect related to recollection was larger for the former than for the latter, indicating that equivalent levels of memory retrieval were achieved through "less" neural correlates of familiarity and recollection. By synthesizing the results of experiment 1 and 2, we believed unitization did not impede overall item recognition performance. [ABSTRACT FROM AUTHOR]