Haley G. Frey¹, David Whitney¹; ¹University of California, Berkeley

Change blindness is a robust phenomenon where attentive observers fail to notice large changes in a visual stimulus, a surprising limitation of visual processing. These failures range from missing a change that coincides with a “mudsplash” or that occurs between two images separated by a blank screen, to failing to notice that the identity of a stranger has changed mid conversation. Individuals will even miss changes in items they are looking right at when the change takes place gradually, a less well-researched phenomenon called slow change blindness. Though there is still uncertainty in what drives the phenomenon of slow change blindness, one theory for how the brain maintains a stable visual representation across time is serial dependence. This proposed mechanism capitalizes on the assumption of an unchanging world and allows us to retain information about our surroundings across different head, body, and object orientations. Serial dependence predicts that perception at any given moment not only reflects currently available visual information, but also pulls from past visual information to stabilize and smooth perception. Recent work shows that after viewing a slowly aging face, observers rate a face as several years younger than just observing the face without any preceding morph. This illusion of stability indicates that past information can bias perception of a current stimulus but does not characterize or measure the moment-to-moment perception that occurs during a continuously changing stimulus. In this study, we present observers with two slowly oscillating stimuli and ask them to make continuous judgements about their similarity over time. We find that observers perceive two phase-shifted slowly changing stimuli to be more similar than they actually are at any moment. This bias is consistent with serial dependence and may provide evidence for the role of such a stabilization mechanism in slow change blindness.