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Explore-Exploit Tradeoffs During Memory Search: The Predictive Role of Theta Oscillations

Poster Session E - Monday, March 9, 2026, 2:30 – 4:30 pm PDT, Fairview/Kitsilano Ballroom

Channing Hambric¹ (), Erika Nyhus¹, Abhilasha Kumar¹; ¹Bowdoin College

Retrieval of concepts from semantic memory involves interactions between several brain regions and a complex interplay of lexical sources. Recent work with the verbal fluency task (VFT; where participants generate as many examples as they can from a given category within a fixed duration) has shown that individuals delicately balance exploiting current clusters (i.e., groups of related items) within semantic memory with exploring new clusters, similar to how animals search for resources in external environments. In this work, we investigated the temporal dynamics of explore-exploit decisions during semantic memory search by examining the role of predictive processing as indexed by theta oscillations using electroencephalography (EEG). Participants completed the VFT and two tasks commonly used to measure predictive processing: the balloon analogue risk task (BART) and the Cloze sentence fragment completion task. We used a computational model to predict explore-exploit decisions while measuring theta oscillatory power via EEG immediately before VFT transitions. We also examined the extent to which the differences in theta power for explore vs. exploit decisions correlate with amplitudes of event-related potentials (ERPs) related to uncertainty-based exploration in the BART task (measured via P300) and prediction of semantic information in the Cloze task (measured via N400). Overall, our results indicate that increases in theta power captured signatures of exploration and exploitation during memory search, and also showed robust correlations with ERPs of predictive processing. These findings suggest that the neural dynamics guiding external navigation also govern internal navigation in memory, consistent with a foraging-based framework of memory search.

Topic Area: LONG-TERM MEMORY: Semantic