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Snakes and ladders: the role of temporal modulation in visual contour integration
- Vision Research
, 2001
"... We investigated temporal aspects of the cortical mechanisms supporting visual contour integration by measuring observers’ efficiency at detecting fragmented contours, composed of Gabor micropatterns, embedded in a field of distractor elements. Gabors consisted of a static Gaussian enveloping a sinus ..."
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Cited by 14 (1 self)
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We investigated temporal aspects of the cortical mechanisms supporting visual contour integration by measuring observers’ efficiency at detecting fragmented contours, composed of Gabor micropatterns, embedded in a field of distractor elements. Gabors consisted of a static Gaussian enveloping a sinusoidal carrier which was temporally modulated by motion or counter-phase flicker. The elements forming the path could be oriented either parallel (‘snakes’) or perpendicular to the contour orientation (‘ladders’). Sensitivity to contour structure (estimated by measuring the maximum tolerable element orientation jitter supporting contour detection) was increased when the elements were drifting or flickering. Snakes were more detectable than ladders under all conditions. The increase in sensitivity conferred by drifting carriers was present even when the elements in the same stimulus were drifting at a range of speeds spanning almost three octaves. These results lend further support to the notion that the contour
Motion processing specialization in Williams syndrome
, 2005
"... Williams syndrome (WS) is a rare genetic disorder characterized by severe spatial deficits and relatively spared language. Although initial research suggested that WS entails a generalized motion processing deficit, later work demonstrated intact biological motion perception in people with WS, refle ..."
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Cited by 8 (0 self)
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Williams syndrome (WS) is a rare genetic disorder characterized by severe spatial deficits and relatively spared language. Although initial research suggested that WS entails a generalized motion processing deficit, later work demonstrated intact biological motion perception in people with WS, reflecting a sparing of a specific motion perception system. The present study examined whether this sparing is unique to biological motion, or extends to other motion tasks as well. WS children and adults and normal controls were tested to examine developmental changes across a variety of motion tasks. Results indicated that WS individuals performed at normal levels for motion coherence and biological motion tasks but had elevated thresholds for the 2-D form-frommotion task, a profile that extended into adulthood. These findings provide evidence that a genetic impairment can lead to a selective motion processing deficit and argue against characterizing WS as including a general motion processing impairment. The nature of the motion deficit is considered, including the implications for WS dorsal/ventral processing.
A theory of dynamic occluded and illusory object perception
- Journal of Experimental Psychology: General
, 2006
"... Humans see whole objects from input fragmented in space and time, yet spatiotemporal object perception is poorly understood. The authors propose the theory of spatiotemporal relatability (STR), which describes the visual information and processes that allow visible fragments revealed at different ti ..."
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Cited by 6 (3 self)
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Humans see whole objects from input fragmented in space and time, yet spatiotemporal object perception is poorly understood. The authors propose the theory of spatiotemporal relatability (STR), which describes the visual information and processes that allow visible fragments revealed at different times and places, due to motion and occlusion, to be assembled into unitary perceived objects. They present a formalization of STR that specifies spatial and temporal relations for object formation. Predictions from the theory regarding conditions that lead to unit formation were tested and confirmed in experiments with dynamic and static, occluded and illusory objects. Moreover, the results support the identity hypothesis of a common process for amodal and modal contour interpolation and provide new evidence regarding the relative efficiency of static and dynamic object formation. STR postulates a mental representation, the dynamic visual icon, that briefly maintains shapes and updates positions of occluded fragments to connect them with visible regions. The theory offers a unified account of interpolation processes for static, dynamic, occluded, and illusory objects.
14. Linking Psychophysics and Physiology of Center-Surround Interactions in Visual Motion Processing
"... The eye is stimulated and informed by continually changing patterns. Images of environmental surfaces move over the retina as the eyes move, and the images expand, contract, and deform as objects move and the observer moves through the environment. The structure of these changing patterns is a princ ..."
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Cited by 3 (1 self)
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The eye is stimulated and informed by continually changing patterns. Images of environmental surfaces move over the retina as the eyes move, and the images expand, contract, and deform as objects move and the observer moves through the environment. The structure of these changing patterns is a principal form of information – about
Superposition catastrophe and form–motion binding.
- Journal of Vision,
, 2008
"... Numerous studies indicate that perceiving global object motion results from the integration of local component motions across space and time. Less attention has been paid to the issue of motion selection, necessary to avoid spurious associations of component motions belonging to different objects a ..."
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Cited by 1 (0 self)
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Numerous studies indicate that perceiving global object motion results from the integration of local component motions across space and time. Less attention has been paid to the issue of motion selection, necessary to avoid spurious associations of component motions belonging to different objects and to solve the so-called "superposition catastrophe problem"
Effects of visual coherence on visuo-manual coordination
"... Strong relationships exist between goal directed action and visual perception, both at the behavioural and cortical level. However, the nature and specificity of these interactions remain poorly understood. Here, we study the interactions between visual motion processing and goal-directed motor cont ..."
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Strong relationships exist between goal directed action and visual perception, both at the behavioural and cortical level. However, the nature and specificity of these interactions remain poorly understood. Here, we study the interactions between visual motion processing and goal-directed motor control in two perceptual-motor tasks involving driving and tracking moving objects of varying coherence. Our re-sults show that overt motor behaviour does not influence perceptual coherence. In contrast, perceptual motion coherence has a strong in-fluence in the tracking task, but a weak effect in the driving task. These findings suggest that perception and action share at least com-mon mechanisms and that motor control depends on the manual task under investigation. 1
