Trends in Cognitive Sciences
ReviewResolving visual motion through perceptual gaps
Section snippets
The challenge of processing motion through perceptual gaps
Incoming visual information is often interrupted by externally and internally driven events such as occlusion (see Glossary) and eyeblinks, producing perceptual gaps (Figure 1). For example, cars moving on a highway are often fully or partially occluded by other traffic. Similarly, eyeblinks, which can occur 15–20 times per min [1] and may last for up to 500 ms [2,3], prevent visual information from reaching the brain. One way of bridging these perceptual gaps is to bias perception towards the
The neural substrates of motion processing
Both physical and illusory motion processing can potentially inform our understanding of how visual motion is resolved through perceptual gaps. Before and after the perceptual gap, the object moves visibly along a motion trajectory. Processing physical motion before the gap informs predictions about the object’s position during the gap. Furthermore, physical motion after the gap can reinforce the perception of an object trajectory retrospectively. Maintenance of a motion trajectory before and
The phenomenology of perceptual gaps
In natural vision, perceptual gaps are frequent, but these interruptions do not break the perceived continuity of motion trajectories. For eyeblinks in particular, it has been suggested that the perception of continuity is supported by both the suppression of the visual consequences of an eyeblink [3] and an underestimation of the eyeblink duration [47., 48., 49., 50.]. In eyeblink suppression, efference copy may trigger preparation for the visual consequences of closing the eyelid by lowering
Where is object information maintained during perceptual gaps?
Multiple motion-sensitive cortical regions have been implicated in maintaining representations during perceptual gaps. Similar to representations during apparent motion [83,84], position-specific information has been shown to be represented in the early visual cortex during perceptual gaps [85., 86., 87.]. In one fMRI study [87], participants viewed an object moving on a circular trajectory that was dynamically occluded in one quadrant. Within retinotopically defined areas of V1, V2, and V3
Concluding remarks
Resolving visual information through perceptual gaps is a fundamental part of everyday vision, as eyeblinks and occlusion occur frequently. Here, we highlighted why moving stimuli pose a particular challenge to bridging perceptual gaps and showed that mechanisms such as suppression, extrapolation, and integration are important to update visual motion through periods of occlusion and eyeblinks.
Generally, the maintenance and updating of motion information occurs automatically and without
Acknowledgments
L.T., G.E., and C.I.B. are supported by the Intramural Research Program of the NIMH (ZIAMH002909). The authors thank Marianne Duyck and Eli Merriam for providing helpful comments on earlier versions of the manuscript.
Declaration of interests
No interests are declared.
Glossary
- Accidental contours
- true object contours mark the shape of an object. By contrast, accidental contours are created by objects being partially occluded, generating a new contour where the objects intersect.
- Apparent motion
- the impression of movement produced by the rapid succession of still objects in different locations.
- Blink suppression
- suppression of the experience of an eyeblink and the sensory input prior and during the eyeblink to support continuous visual perception throughout eyeblinks.
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