Huiyu Ding¹, Jonathon Whitlock², Lili Sahakyan¹; ¹University of Illinois Urbana-Champaign, ²Mississippi State University

Forgetting is an adaptive mechanism and the desired cognitive outcome, especially active forgetting, when information is unwanted, irrelevant, or even traumatic. Importantly, successful active forgetting is associated with distinct neural recruitment and viewing patterns compared to passive forgetting. The current study explored the physiological marker for active forgetting by monitoring pupil fluctuation, a measurement linked to long-term memory retrieval, in a modified item-method directed forgetting procedure. The current study explored the physiological markers for active forgetting by monitoring pupil fluctuations in an item-method directed forgetting study. At learning, participants studied naturalistic scene images, each followed by a Remember or Forget instruction. At test, participants were presented with either the identical images or the mirrored version of a studied image and had to determine whether the image was old or new. Active forgetting is defined as when forget-cue images are subsequently forgotten. Passive forgetting is defined as when remember-cued images are subsequently forgotten. The findings revealed that active forgetting elicited greater pupil dilation than passive forgetting. In a follow-up experiment, we strengthened a subset of items by repetition to determine whether the observed pattern in Experiment 1 was driven solely by differences in memory strength. In Experiment 2, we did not observe similar patterns, as weakly encoded images produced pupil fluctuations of similar magnitude to strongly encoded images. Together, these results suggest that the success of intentional forgetting is reflected in pupil fluctuations during memory retrieval, potentially indicating the active cognitive processes engaged by participants in response to forget instructions.