Kinetic Occlusion Research Articles

Age-related Differences in Edge Discrimination through Kinetic Occlusion

Age-related Differences in Edge Discrimination through Kinetic Occlusion

Perception of a surface split induced by globally inconsistent kinetic occlusion: Objects with salient parts break apart easily.

Unlike previous studies of part-based shape representations that mostly investigated static images, we tested whether part segmentation can affect the perception of ambiguous dynamic events, involving globally inconsistent kinetic occlusion: An object moved horizontally across another stationary object, with either its top or bottom half occluding and the other half being occluded by the stationary one, which could be perceived as one object being split into halves by the other object. We manipulated an object's part structure by introducing concave or convex cusps along the contour of an object and found that objects with concave cusps were more likely perceived as being split than those with no or convex cusps. This study provides a new insight into a broad framework of spatiotemporal perceptual organization, by demonstrating that salient parts are readily perceived as broken apart in a physical sense, which in turn alters the perception of a motion event and its causal structure. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Supplemental Material for Perception of a Surface Split Induced by Globally Inconsistent Kinetic Occlusion: Objects With Salient Parts Break Apart Easily

Supplemental Material for Perception of a Surface Split Induced by Globally Inconsistent Kinetic Occlusion: Objects With Salient Parts Break Apart Easily

Apparent motion induced by illusory kinetic occlusion of an object blinking in place

Apparent motion induced by illusory kinetic occlusion of an object blinking in place

Curvature Discrimination through Kinetic Occlusion

Curvature Discrimination through Kinetic Occlusion

Edge Detection through Kinetic Occlusion: The Role of Spatial and Temporal Integration

Edge Detection through Kinetic Occlusion: The Role of Spatial and Temporal Integration

Perception of a surface split induced by globally inconsistent kinetic occlusion: Objects composed of salient parts break apart easily

Perception of a surface split induced by globally inconsistent kinetic occlusion: Objects composed of salient parts break apart easily

A neural model of border-ownership from kinetic occlusion.

Camouflaged animals that have very similar textures to their surroundings are difficult to detect when stationary. However, when an animal moves, humans readily see a figure at a different depth than the background. How do humans perceive a figure breaking camouflage, even though the texture of the figure and its background may be statistically identical in luminance? We present a model that demonstrates how the primate visual system performs figure-ground segregation in extreme cases of breaking camouflage based on motion alone. Border-ownership signals develop as an emergent property in model V2 units whose receptive fields are nearby kinetically defined borders that separate the figure and background. Model simulations support border-ownership as a general mechanism by which the visual system performs figure-ground segregation, despite whether figure-ground boundaries are defined by luminance or motion contrast. The gradient of motion- and luminance-related border-ownership signals explains the perceived depth ordering of the foreground and background surfaces. Our model predicts that V2 neurons, which are sensitive to kinetic edges, are selective to border-ownership (magnocellular B cells). A distinct population of model V2 neurons is selective to border-ownership in figures defined by luminance contrast (parvocellular B cells). B cells in model V2 receive feedback from neurons in V4 and MT with larger receptive fields to bias border-ownership signals toward the figure. We predict that neurons in V4 and MT sensitive to kinetically defined figures play a crucial role in determining whether the foreground surface accretes, deletes, or produces a shearing motion with respect to the background.

A neural model of visual figure-ground segregation from kinetic occlusion

Freezing is an effective defense strategy for some prey, because their predators rely on visual motion to distinguish objects from their surroundings. An object moving over a background progressively covers (deletes) and uncovers (accretes) background texture while simultaneously producing discontinuities in the optic flow field. These events unambiguously specify kinetic occlusion and can produce a crisp edge, depth perception, and figure-ground segmentation between identically textured surfaces — percepts which all disappear without motion. Given two abutting regions of uniform random texture with different motion velocities, one region appears to be situated farther away and behind the other (i.e., the ground) if its texture is accreted or deleted at the boundary between the regions, irrespective of region and boundary velocities. Consequently, a region with moving texture appears farther away than a stationary region if the boundary is stationary, but it appears closer (i.e., the figure) if the boundary is moving coherently with the moving texture. A computational model of visual areas V1 and V2 shows how interactions between orientation- and direction-selective cells first create a motion-defined boundary and then signal kinetic occlusion at that boundary. Activation of model occlusion detectors tuned to a particular velocity results in the model assigning the adjacent surface with a matching velocity to the far depth. A weak speed-depth bias brings faster-moving texture regions forward in depth in the absence of occlusion (shearing motion). These processes together reproduce human psychophysical reports of depth ordering for key cases of kinetic occlusion displays.

Effects of contrast on spatial and temporal integration in 2D shape perception from dynamic occlusion

In self-motion, research has shown that optic flow can be a source that supplies essential information about heading, speed, and characteristics of the surrounding environment. Evidence has shown that increases in optic flow quality and quantity have additive effects on steering performance. Further, studies have shown that spatial integration (e.g., stimuli density) and temporal integration (e.g., stimuli lifetime) may play a key role in motion perception. In the current study, we examined how spatial and temporal integration are affected by the quality of optic flow in generating 2-D shape perception. Participants were asked to identify a 2D shape resulting from kinetic occlusion information. Displays consisted of 2D arrays of dots forming both foreground objects and the background texture. When the foreground object moves the disappearance and reappearance of back ground dots can be used to recover the object shape. Three experiments were conducted in which optic flow density, display contrast, and optic flow lifetime were variables of interest. In each of the three experiments, the threshold of one variable was measured, using a four-alternative forced choice staircase, while the other two variables were manipulated. In experiment 1, optical flow density threshold was measured for 8 participants using a 2 (contrast) by 2 (lifetime) within-subjects design; in experiment 2, contrast threshold was measured for 5 participants using a 3 (density) by 3 (lifetime) within-subjects design; in experiment 3, lifetime threshold was measured for 5 participants using a 3 (density) by 3 (contrast) within-subjects design. The results showed the performance in 2D shape perception decreased as a function of decreased contrast, decreased lifetime, and decreased density. These results suggest the spatial and temporal integration might be potential predictors of driving performance under low contrast conditions. Meeting abstract presented at VSS 2012

Representation of motion onset and offset in an augmented Barlow-Levick model of motion detection

Kinetic occlusion produces discontinuities in the optic flow field, whose perception requires the detection of an unexpected onset or offset of otherwise predictably moving or stationary contrast patches. Many cells in primate visual cortex are directionally selective for moving contrasts, and recent reports suggest that this selectivity arises through the inhibition of contrast signals moving in the cells’ null direction, as in the rabbit retina. This nulling inhibition circuit (Barlow-Levick) is here extended to also detect motion onsets and offsets. The selectivity of extended circuit units, measured as a peak evidence accumulation response to motion onset/offset compared to the peak response to constant motion, is analyzed as a function of stimulus speed. Model onset cells are quiet during constant motion, but model offset cells activate during constant motion at slow speeds. Consequently, model offset cell speed tuning is biased towards higher speeds than onset cell tuning, similarly to the speed tuning of cells in the middle temporal area when exposed to speed ramps. Given a population of neurons with different preferred speeds, this asymmetry addresses a behavioral paradox—why human subjects in a simple reaction time task respond more slowly to motion offsets than onsets for low speeds, even though monkey neuron firing rates react more quickly to the offset of a preferred stimulus than to its onset.

Spatio-temporal integration, kinetic occlusion and aging

Spatio-temporal integration, kinetic occlusion and aging

Aging and visual processing: Declines in spatial not temporal integration

Age-related declines in vision are well documented in the literature. In the present study we examined whether changes in spatial or temporal integration contribute to this decline. Younger (mean age of 21) and older (mean age of 745) subjects were asked to identify 2D shapes based on kinetic occlusion information---the accretion and deletion of texture during motion. The results of the first experiment indicated age-related decrements in spatial but not temporal integration. In the second experiment we manipulated the lifetime of motion stimuli to more directly examine temporal integration. The results indicated no differential effect of age on temporal integration. The results considered together suggest age related changes in recovering 2D shape from occlusion are the result of spatial but not temporal integration. Age-related changes in neural inhibition and ACh for regulating spatial integration are proposed as possible mechanisms for this decline.

Phenomenal Permanence and the Development of Predictive Tracking in Infancy

The perceived spatiotemporal continuity of objects depends on the way they appear and disappear as they move in the spatial layout. This study investigated whether infants' predictive tracking of a briefly occluded object is sensitive to the manner by which the object disappears and reappears. Five-, 7-, and 9-month-old infants were shown a ball rolling across a visual scene and briefly disappearing via kinetic occlusion, instantaneous disappearance, implosion, or virtual occlusion. Three different measures converged to show that predictive tracking increased with age and that infants were most likely to anticipate the reappearance of the ball following kinetic occlusion. These results suggest that infants' knowledge of the permanence and nonpermanence of objects is embodied in their predictive tracking.

A bayesian analysis of kinetic occlusion for 2-D shape perception

A bayesian analysis of kinetic occlusion for 2-D shape perception

Linear vection in the central visual field facilitated by kinetic depth cues.

Illusory self-motion (vection) is thought to be determined by motion in the peripheral visual field, whereas stimulation of more central retinal areas results in object-motion perception. Recent data suggest that vection can be produced by stimulation of the central visual field provided it is configured as a more distant surface. In this study vection strength (tracking speed, onset latency, and the percentage of trials where vection was experienced) and the direction of self-motion produced by displays moving in the central visual field were investigated. Apparent depth, introduced by using kinetic occlusion information, influenced vection strength. Central displays perceived to be in the background elicited stronger vection than identical displays appearing in the foreground. Further, increasing the eccentricity of these displays from the central retina diminished vection strength. If the central and peripheral displays were moved in opposite directions, vection strength was unaffected, and the direction of vection was determined by motion of the central display on almost half of the trials when the centre was far. Near centres produced fewer centre-consistent responses. A complete understanding of linear vection requires that factors such as display size, retinal locus, and apparent depth plane are considered.

Kinetic occlusion: Further studies of the boundary-flow cue

Previous work has demonstrated that human beings employ a processing assumption, the boundary-flow constraint, in perceiving the order of depth at an edge. Subjects perceive depth order of surfaces on the basis of the relative motions of an image boundary and a projected surface texture on either side of the boundary. In the present study, adult subjects viewed computer-generated kinematograms in which boundary-flow information provided the only cue for depth order. The results of Experiments 1 and 2 indicate that common motion between boundary and texture and differential motion between boundary and texture can independently generate the perception of ordered depths of surfaces. In Experiment 3, we examined the interaction of two processes involved in the extraction of depth order from boundary-flow displays: (1) the propagation of foreground and background surfaces from texture to boundary; and (2) the computation of depth order of surfaces on either side of the boundary. The results indicate that while the mechanism that computes depth from boundary-flow information functions reliably when the mean distance between texture and boundary is 8.1(0), surface propagation may be disrupted for distances of this magnitude.

仮現運動による動的遮蔽を決定する奥行き手がかり

In the present study, we examined the range of conditions which produced kinetic occlusion by apparent movement. Specifically, it was attempted to clarify the relation between apparent kinetic occlusion and depth cues, especially in connection with timing factors. The depth cues used in the experiment were based on size, luminance and shape of stimuli

The effects of kinetic occlusion and categorization on amodal completion: A comment on Gerbino and Salmaso (1987)

The experimental study of Gerbino and Salmaso (1987) focused on the process of amodal completion, i.e. the process that leads to the impression of a total pattern in the absence of information about all parts of the pattern. One of the questions that they have attempted to answer with respect to this process is whether or not it depends on the categorization of the modal part (i.e. the part about which visual information is present) as a modification of a complete prototype. The major conclusion of their experiments is that amodal completion does not depend upon categorization. Furthermore, they interpret their results as indicating that neither the truncated form of the occluded part nor the unification/segregation of contour segments are phenomenally real. We designed some variants of the tunnel effect to demonstrate (1) that the explicit categorization of some parts of the input can have an influence on amodal completion and (2) that the truncated form of a pattern can be phenomenally real. Our results corroborate these hypotheses and can, therefore, be interpreted as refuting two rather central claims of Gerbino and Salmaso (1987). The conclusion of our experiment must be that amodal completion is not as primary as they have supposed but can be influenced by kinetic occlusion and categorization stored in visual memory.

2-D contour perception resulting from kinetic occlusion.

Kinetic occlusion, the progressive deletion or accretion of texture elements as one surface covers or uncovers another, has been shown to be an important source of information for determining depth order. In the present study, the importance of this information for 2-D contour perception was examined. In Experiment 1, subjects were asked to discriminate four different target shapes defined solely by kinetic occlusion. Discrimination increased with an increase in texture density and velocity, with density as the major factor. In Experiment 2, the targets were defined by static untextured regions as well as by kinetic occlusion. Overall, accuracy was similar to that found in Experiment 1, indicating that the presence of static information had little impact on accuracy. In Experiment 3, subjects were unable to discriminate among the four targets when presented with static versions of the displays used in Experiment 2. The results from these experiments indicate that kinetic occlusion can be used for discrimination of different 2-D shapes and that density has a more important role in determining accuracy than velocity.