Abstract
Despite a noisy and ever-changing visual world, our visual experience appears remarkably stable over time. Serial dependencies, which bias our percepts toward past stimuli, were proposed as a mechanism to facilitate perceptual stability: by smoothing the appearance of changes in the environment, the world looks more stable than it would otherwise. Here, we introduce a new visual illusion, which shows direct evidence of the causal link between serial dependence, change blindness, and perceptual stability. In a single-trial, single-shot experiment, 300 observers attended to a 30 second video in which a face aged from young-to-old (or old-to-young). At the end of the video, after a gap, observers reported the age of a visible test face that was physically identical to the last face in the video. The rated age of the test face was strongly biased towards the earlier faces seen in the video. Because of serial dependence, the identity of the face is continuously merged over time and, as a result, observers perceive a slower age change. In a second experiment, observers viewed the same videos, followed by a test face that jumped forward or backward in age, physically older or younger than the last frame of the video. We measured discrimination accuracy as a function of the difference in age between the last frame of the video and the test face. Sensitivity to the age jump was lowest when the test face jumped backward, toward a previously seen age. Because of serial dependence, the face in the video was perceived to age at a slower rate, and this caused a change blindness selectively for the backward jumping faces. The illusion shows for the first time how serial dependence can make us blind to temporal changes in the environment by actively smoothing the appearance of objects, thus maximizing perceptual stability.