Motion perception induced by dynamic grouping: a probe for the compositional structure of objects (original) (raw)
Related papers
International Journal of Imaging Systems and Technology, 1996
We present a series of experiments whose results show strong similarities between textural grouping and motion experiments. A family of stimuli consisting of elements of different colors, luminancepolarity, and orientation are used in experiments in both eliciting textural grouping and detection of apparent motion. Among the similarities are that the orientation attribute is a weaker attribute than either color or luminance polarity in eliciting both textural grouping and in detection of apparent motion. However, if the orientation elements are collinear they become salient and contribute toward grouping and apparent motion. The results also indicate that chromatic mechanisms play a significant role in both texture and motion perception. The similarity suggests that perceptual rules governing spatial grouping are analogous to those governing spatiotemporal grouping. The results of these experiments could be used in the areas of image segmentation, pattern recognition, and scientific visualization.
Dynamics of perceptual grouping: similarities in the organization of visual and auditory groups
In vision, the Gestalt principles of perceptual organization are generally well understood and remain a subject of detailed analysis. However, the possibility for a unified theory of grouping across visual and auditory modalities remains largely unexplored. Here we present examples of auditory and visual Gestalt grouping, which share important organizational properties. In particular, similarities are revealed between grouping processes in apparent motion, auditory streaming, and static 2-D displays. Given the substantial difference in the context, within which the phenomena in question occur (auditory vs. visual, static vs. dynamic), these similarities suggest that the dynamics of perceptual organization could be associated with a common (possibly central) mechanism. If the relevance of supramodal invariants of grouping is granted, the question arises as to whether they can be studied empirically. We propose that a force-field theory, based on a differential-geometric interpretation of perceptual space could provide a suitable starting point for a systematic exploration of the subjective properties of certain classes of auditory and visual grouping phenomena.
Natural groups of transformations underlying apparent motion and perceived object shape and color
Shepard's analysis of how shape, motion, and color are perceptually represented can be generalized. Apparent motion and shape may be associated with a group of spatial transformations, accounting for rigid and plastic motion, and perceived object color may be associated with a group of illuminant transformations, accounting for the discriminability of surface-reflectance changes and illuminant changes beyond daylight. The phenomenological and mathematical parallels between these perceptual domains may indicate common organizational rules, rather than specific ecological adaptations.
Visual Motion and the Perception of Surface Material
Current Biology
Many critical perceptual judgments, from telling whether fruit is ripe, to determining whether the ground is slippery, involve estimating the material properties of surfaces. Very little is known about how the brain recognizes materials, even though the problem is likely as important for survival as navigating or recognizing objects. Though previous research has focused nearly exclusively on the properties of static images , recent evidence suggests that motion may affect the appearance of surface material . However, what kind of information motion conveys and how this information may be used by the brain is still unknown. Here, we have identified three motion cues that the brain could rely on to distinguish between matte and shiny surfaces. We show that these motion measurements can override static cues, leading to dramatic changes in perceived material depending on the image motion characteristics. A classifier algorithm based on these cues correctly predicts both successes and some striking failures of human material perception. Together these results reveal a previously unknown use for optic flow in the perception of surface material properties.
Interaction between complex motion patterns in the perception of shape
Vision Research, 2008
We investigated how different types of complex motion patterns interact in the perception of shape. We used global dot-motion stimuli which consisted of two superimposed groups of dots; one group of dots moved along an ellipsoidal trajectory (target pattern), while the other group of dots was divided into quadrants with dots in alternating sectors moving in radial expanding and radial contracting directions (background pattern). In the first experiment, observers judged whether the major axis of an ellipsoidal motion pattern oriented at 45°or À45°from vertical lay to the right or to the left of a central vertical line. Ellipsoids with different aspect ratios, which controlled both the tilt (left or right of vertical) and the extent of ellipsoidal curvature, were presented to observers using method of constant stimuli. The appearance of the ellipsoidal target pattern was distorted in the presence of background motion. The aspect ratio of the target at which observers perceived the figure to be circular was approximately 0.86 (an aspect ratio of 1.0 indicates a circle), with the pattern's major axis lying in the two sectors that contained contracting motion. This finding may constitute evidence that background motion distorts the perception of space, resulting in a distorted target pattern. However, the distortion effect is limited to conditions for which the speed of the target pattern and background pattern was slow and high contrast, and for when dots forming the target and background patterns were of the same luminance polarity.
The role of temporal structure in human vision
2005
Gestalt psychologists identified several stimulus properties thought to underlie visual grouping and figure/ground segmentation, and among those properties was common fate: the tendency to group together individual objects that move together in the same direction at the same speed. Recent years have witnessed an upsurge of interest in visual grouping based on other timedependent sources of visual information, including synchronized changes in luminance, in motion direction, and in figure/ ground relations. These various sources of temporal grouping information can be subsumed under the rubric temporal structure. In this article, the authors review evidence bearing on the effectiveness of temporal structure in visual grouping. They start with an overview of evidence bearing on temporal acuity of human vision, covering studies dealing with temporal integration and temporal differentiation. They then summarize psychophysical studies dealing with figure/ground segregation based on temporal phase differences in deterministic and stochastic events. The authors conclude with a brief discussion of neurophysiological implications of these results.