Target detection enhances relational processing of background items: evidence from associative recognition paradigms and EEG

BACKGROUND: The Attentional Boost Effect (ABE) refers to the enhancement of memory for concurrently presented background information when target detection is performed during encoding. However, there is still controversy regarding whether ABE-related manipulations can both enhance item-specific and relational processing. Given that resolving this issue can enhance our understanding of the generality of the ABE, we will validate this issue and explore its underlying neural mechanisms. METHODS: The current study combined the ABE paradigm with the associative recognition paradigm and employed compound pairs and unrelated pairs as memory materials to manipulate the reliance on item-specific or relational information, using a 2 (detection stimulus type: target vs. distractor) × 2 (word pair: compound vs. unrelated) within-subject design. Furthermore, we conducted event-related potential (ERP) and time-frequency analyses (TFA) on participants' electrophysiological data during associative recognition to further explore the underlying neural mechanisms of the ABE. RESULTS: The results showed that, behaviorally, participants remembered more target-paired pairs than distractor-paired pairs for both types of word pairs, demonstrating an ABE. In the ERP results, target word pairs evoked a significant FN400 effect, related to familiarity, whereas distractor word pairs did not evoke this effect. Furthermore, for compound pairs, target pairs evoked larger LPC effects than distractor pairs, which were related to recollection; however, for unrelated pairs, there was no difference in the LPC effect between target and distractor pairs. The TFA results showed that target word pairs induced lower gamma-band activity than distractor word pairs, reflecting familiarity processing. CONCLUSIONS: Taken together, target detection enhanced associative memory performance, indicating that ABE-related manipulations can both facilitate item-specific and relational processing. At the neural mechanism level, ABE-related manipulations enhanced the contribution of familiarity in associative recognition, and when the semantic association between items was stronger, ABE-related manipulations further enhanced recollection.