Representation of an object through visual occlusion

We have strong predictions about what happens to an object when it becomes occluded during motion. Here, we used three separate tasks to examine the underlying mechanisms supporting object tracking through periods of occlusion. In the first experiment (n=21), we tested if accurate extrapolation of an object's position into the occluder was modulated by time. In each trial, an object moved horizontally before becoming occluded. Object movement was associated with a sound, traveling at one of three speeds. Behind the occluder, the sound stopped indicating that the object stopped moving. Participants indicated where the object stopped moving, revealing they consistently lagged behind the true object position. The error increased with occlusion time and faster speeds. Estimated positions and eye movements were highly correlated. In the second experiment (n=20), we tested whether spatiotemporal continuity could be perceived across occlusion. Starting at one velocity, the object became occluded and reappeared after occlusion. During occlusion, the object sped up, slowed down, or moved at initial velocity. The participant was asked if the object reappeared too early or too late. We found that participants were highly accurate at determining these speed modifications, suggesting continuity can be achieved regardless of poor representation during occlusion as observed in experiment one. One possibility for the disparity in performance between the first two experiments is that post-occlusion information is critical for bridging the occlusion period. We therefore asked participants in the third experiment (n=21) to estimate when the object reached the end of the occluder, beginning to re-emerge. We found consistently late estimation of object reappearance time regardless of object speed, indicating that post-occlusion information is critical to perceptual continuity. We provide evidence of brief extrapolation into the occluder without accurately bridging the entire occluder. When post-occlusion information is available, the occlusion period can be accurately reconstructed.