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Accounting for experimental factors diminishes neural measures of subsequent memory

Poster Session D - Monday, March 9, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom
Also presenting in Data Blitz Session 1 - Saturday, March 7, 2026, 10:30 am – 12:00 pm PST, Salon ABC.

Riley DeHaan¹ (), David Halpern², Michael Kahana¹; ¹University of Pennsylvania, ²Columbia University

Decades of work have shown that neural activity at the time of item study predicts subsequent memory performance. However, it is known that items at the beginnings and ends of lists are successfully recalled most often, that some items are more memorable than others, and that these effects vary widely across individuals. This raises the question of whether neural activity correlated with memory primarily reflects internal fluctuations in the brain relating to the ability to memorize new items (which should be targetable by interventions such as brain stimulation) or instead corresponds to the behavioral effects of experimental stimuli (which may be harder to modulate). Here we compare estimates of the subsequent memory effect computed with and without adjustments for experimental variables including study position and item identity in a sample of 375 patients recorded intracranially during a free recall task. After incorporating stimulus-related effects, neural activity remains a significant behavioral predictor but only explains an additional 3.9% of the variance in recall performance, suggesting the majority of the subsequent memory effect should be attributed to stimulus features rather than an endogenous state of memory performance. We decompose the subsequent memory effect across stimulus features and anatomical regions to reveal the regions associated with variability in memory uniquely explained by item identity, study position, and the residual memory variability unexplained by stimulus features. Our findings indicate that isolating neural activity corresponding to an endogenous state of learning readiness requires careful consideration of experimental confounds.

Topic Area: LONG-TERM MEMORY: Episodic