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An electrophysiological investigation into the objective and subjective aspects of episodic memory

Poster Session F - Tuesday, March 10, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Pearl S. Peng¹ (), Preston P. Thakral¹; ¹Smith College

In the laboratory, episodic memory (i.e., memory for specific and personal past events) is typically assessed using one of two approaches. Objective assessments require participants to retrieve a specific contextual detail from a studied episode (e.g., source memory for spatial context). In contrast, subjective assessments rely on introspective judgments such as those in the ‘Remember/Know’ procedure, in which participants discriminate between test items associated with the retrieval of any qualitative information (‘Remember’) relative to those recognized solely based on an acontextual sense of familiarity (‘Know’). While functional magnetic resonance imaging data indicate that there exist unique brain regions that support objective and subjective assessments of episodic memory, it remains unclear whether the retrieval processes underlying them differentiate over time. To address this question, we utilized electroencephalographic event-related potentials (ERPs), a technique with high temporal resolution. ERPs were recorded during a memory test phase where participants made both objective (spatial source memory) and subjective (Remember-Know) judgments for each test item. Analyses focused on the late positive component (LPC), a parietal ERP component canonically linked to successful episodic memory, emerging between 500-800 milliseconds post-stimulus onset. Results indicated that the LPC was exclusively sensitive to the subjective experience of recollection, such that ‘Remember’ responses elicited significantly greater activity compared to ‘Know’ responses, regardless of source accuracy. These findings are the first to indicate that the LPC is differentially sensitive to subjective and objective aspects of episodic memory, and are consistent with proposals linking the parietal cortex to the phenomenal experience of recollection.

Topic Area: LONG-TERM MEMORY: Episodic