Going, going, gone: localizing abrupt offsets of moving objects.
When a moving object abruptly disappears, this profoundly influences its localization by the visual system. In Experiment 1, 2 aligned objects moved across the screen, and 1 of them abruptly disappeared. Observers reported seeing the objects misaligned at the time of the offset, with the continuing object leading. Experiment 2 showed that the perceived forward displacement of the moving object depended on speed and that offsets were localized accurately. Two competing representations of position for moving objects are proposed: 1 based on a spatially extrapolated internal model, and the other based on transient signals elicited by sudden changes in the object trajectory that can correct the forward-shifted position. Experiment 3 measured forward displacements for moving objects that disappeared only for a short time or abruptly reduced contrast by various amounts. Manipulating the relative strength of the 2 position representations in this way resulted in intermediate positions being perceived, with weaker motion signals or stronger transients leading to less forward displacement. This 2-process mechanism is advantageous because it uses available information about object position to maximally reduce spatio-temporal localization errors.
Maus
Gerrit W
GW
Psychology Department, University of Sussex, Brighton, United KIngdom. gwmaus@ucdavis.edu
Nijhawan
Romi
R
D001288:Attention; D002755:Choice Behavior; D015350:Contrast Sensitivity; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D009039:Motion Perception; D009903:Optical Illusions; D009949:Orientation; D010364:Pattern Recognition, Visual; D010470:Perceptual Masking; D011597:Psychomotor Performance; D011601:Psychophysics; D011930:Reaction Time; D012684:Sensory Thresholds; D014794:Visual Fields