From encoding to retrieval: Change in level of unitization resolves debate about Unitization's effect on associative recognition

Abstract

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.

Changes in the level of unitization moderate the impact of unitization on associative memory

“…Surprisingly, nearly 40% of previous studies has overlooked this factor Kriukova et al, 2013;Li et al, 2017;Rhodes & Donaldson, 2007Tibon et al, 2014;Zheng, Li, Xiao, Broster, & Jiang, 2015;Zheng, Li, Xiao, Broster, Jiang, & Xi, 2015). Experimental evidence supporting this finding has been demonstrated by Ahmad and Hockley (2014), Delhaye et al (2019), andLiu et al (2022). During the encoding phase, participants were instructed to learn either compound versus non-compound words (Ahmad & Hockley, 2014;Liu et al, 2022) or related versus unrelated word pairs (Delhaye et al, 2019).…”

“…One effective strategy is unitization, which involves unitizing two or more pieces of information into a whole (Graf & Schacter, 1985). Over the past two decades, a growing number of behavioral studies (Ahmad & Hockley, 2014Liu et al, 2020Liu et al, , 2021Parks & Yonelinas, 2015), event-related potential (ERP) studies (Bader et al, 2010;Han et al, 2018Han et al, , 2022Li et al, 2019;Liu et al, 2022;Tibon et al, 2014), lesion studies (Borders et al, 2017;Quamme et al, 2007), and ageing studies (Ahmad et al, 2015;Delhaye et al, , 2019Zheng, Li, Xiao, Broster, & Jiang, 2015) have focused on the effect of unitization on associative memory and its underlying processes, namely, familiarity-refers to the sensation of having previously encountered items without the retrieval of contextual details and recollection-recovers additional contextual details about when and/or where the items were encountered (Mandler, 1980;Yonelinas, 2002;Yonelinas et al, 2010).…”

“…There are two typical approaches to manipulate the level of unitization: Compound versus non-compound words (e.g., traffic-jam vs. pool-parlor) and related versus unrelated pairs (e.g., apple-peach vs. cat-lily). Several studies have manipulated the level of unitization using compound versus non-compound words, yielding conflicting findings regarding its facilitation on associative memory (facilitate: Li et al, 2021;Liu et al, 2020Liu et al, , 2022; no facilitate: Ahmad & Hockley, 2017;Ford et al, 2010). When examining its effects on familiarity and recollection, most of these studies agreed that an increased level of unitization could enhance familiarity Li et al, 2017Li et al, , 2019Liu et al, 2020), but they disagreed on its effect on recollection, with mixed findings of improvement (Li et al, 2019;Liu et al, 2021;Zheng, Li, Xiao, Broster, Jiang, & Xi, 2015) or no effect Li et al, 2017;Li et al, 2021).…”

Effects of congruent emotional contexts during encoding on recognition: An ERPs study

“…Past studies (Feyereisen, 2009; Ouwehand et al., 2019; van Kesteren et al., 2013) have indicated that congruent information bolsters source recognition, likely due to a semantically congruent linkage between the item and its emotional context. Such enhancement may stem from schema‐supported encoding, wherein the congruent emotional context and word merge into a unified representation (Liu et al., 2023; Lyu et al., 2018). This integration showcases a memory advantage by encapsulating emotional attributes.…”

Neural distinctiveness and discriminability in regions of the core network representations support associative unitization

“…Additonally, Huffer and colleagues (2022), show that unrelated, yet unitized object pairs result in better associative memory compared to a non-unitized presentation of the object pairing. Importantly, unitization instructions have been shown to improve associative memory in older adults (Kamp et al, 2018; Liu et al, 2022; Overman & Stephens, 2013; Zheng et al, 2016) by increasing both recollection and familiarity-based responding (e.g., Liu et al, 2022).…”