scholarly journals Asymmetric global motion integration in drifting Gabor arrays

2014 ◽  
Vol 14 (8) ◽  
pp. 18-18 ◽  
Author(s):  
A. T. Rider ◽  
P. W. McOwan ◽  
A. Johnston
Keyword(s):  
Global Motion ◽  
Motion Integration

scholarly journals The integration of local chromatic motion signals is sensitive to contrast polarity

2011 ◽  
Vol 28 (3) ◽  
pp. 239-246 ◽  
Author(s):  
SOPHIE M. WUERGER ◽  
ALEXA RUPPERTSBERG ◽  
STEPHANIE MALEK ◽  
MARCO BERTAMINI ◽  
JASNA MARTINOVIC
Keyword(s):  
Random Motion ◽  
Coherent Motion ◽  
Global Motion ◽  
Local Motion ◽  
Chromatic Contrast ◽  
Motion Direction ◽  
Contrast Polarity ◽  
Motion Integration ◽  
Integration Mechanisms ◽  
Contrast Thresholds

AbstractGlobal motion integration mechanisms can utilize signals defined by purely chromatic information. Is global motion integration sensitive to the polarity of such color signals? To answer this question, we employed isoluminant random dot kinematograms (RDKs) that contain a single chromatic contrast polarity or two different polarities. Single-polarity RDKs consisted of local motion signals with either a positive or a negative S or L–M component, while in the different-polarity RDKs, half the dots had a positive S or L–M component, and the other half had a negative S or L–M component. In all RDKs, the polarity and the motion direction of the local signals were uncorrelated. Observers discriminated between 50% coherent motion and random motion, and contrast thresholds were obtained for 81% correct responses. Contrast thresholds were obtained for three different dot densities (50, 100, and 200 dots). We report two main findings: (1) dependence on dot density is similar for both contrast polarities (+S vs. −S, +LM vs. −LM) but slightly steeper for S in comparison to LM and (2) thresholds for different-polarity RDKs are significantly higher than for single-polarity RDKs, which is inconsistent with a polarity-blind integration mechanism. We conclude that early motion integration mechanisms are sensitive to the polarity of the local motion signals and do not automatically integrate information across different polarities.

scholarly journals Global motion with multiple Gabors - A tool to investigate motion integration across orientation and space

2010 ◽  
Vol 6 (6) ◽  
pp. 1084-1084 ◽  
Author(s):  
S. Nishida ◽  
K. Amano ◽  
M. Edwards ◽  
D. R. Badcock
Keyword(s):  
Global Motion ◽  
Motion Integration

Effect of Spatial Configuration of Motion Signals on Motion Integration across Space

2004 ◽  
Vol 63 (3) ◽  
pp. 173-182 ◽  
Author(s):  
Nobuko Takahashi
Keyword(s):  
Spatial Structure ◽  
Spatial Configuration ◽  
Considerable Effect ◽  
Global Motion ◽  
Local Motion ◽  
Motion Integration

The present study examined the effect of the spatial configuration of local signals on motion integration across space. The perceived coherency was measured in different configurations of apertures and combinations of motion directions. The results showed the following. (1) Motion integration across separate apertures is affected by the spatial configuration of the apertures. The perceived coherency was highest when the apertures were arranged symmetrically with respect to the coherent direction. (2) Though the spatial configuration of apertures are the same, the assignment of each local motion to each apertures has an effect, and converging local motions are integrated more than diverging local motions. (3) There is a limit to the direction difference of local motions. These results suggest that the spatial structure of global motion behind apertures has a considerable effect on the integration of local motions in apertures.

scholarly journals Selective impairment of global motion integration, but not global form detection, in schizophrenia and bipolar affective disorder

2016 ◽  
Vol 3 ◽  
pp. 11-14 ◽  
Author(s):  
Daniel Bennett ◽  
Amy Dluzniak ◽  
Simon J. Cropper ◽  
Timea Partos ◽  
Suresh Sundram ◽  
...  
Keyword(s):  
Affective Disorder ◽  
Bipolar Affective Disorder ◽  
Global Motion ◽  
Motion Integration ◽  
Global Form ◽  
Selective Impairment

When S-cones contribute to chromatic global motion processing

2007 ◽  
Vol 24 (1) ◽  
pp. 1-8 ◽  
Author(s):  
ALEXA I. RUPPERTSBERG ◽  
SOPHIE M. WUERGER ◽  
MARCO BERTAMINI
Keyword(s):  
Motion Processing ◽  
Current Debate ◽  
Color Contrast ◽  
Global Motion ◽  
Motion Direction ◽  
Motion Integration ◽  
Conflicting Evidence ◽  
Simple Detection ◽  
The Individual ◽  
Contrast Thresholds

There is common consensus now that color-defined motion can be perceived by the human visual system. For global motion integration tasks based on isoluminant random dot kinematograms conflicting evidence exists, whether observers can (Ruppertsberg et al., 2003) or cannot (Bilodeau & Faubert, 1999) extract a common motion direction for stimuli modulated along the isoluminant red-green axis. Here we report conditions, in which S-cones contribute to chromatic global motion processing. When the display included extra-foveal regions, the individual elements were large (∼0.3°) and the displacement was large (∼1°), stimuli modulated along the yellowish-violet axis proved to be effective in a global motion task. The color contrast thresholds for detection for both color axes were well below the contrasts required for global motion integration, and therefore the discrimination-to-detection ratio was >1. We conclude that there is significant S-cone input to chromatic global motion processing and the extraction of global motion is not mediated by the same mechanism as simple detection. Whether the koniocellular or the magnocellular pathway is involved in transmitting S-cone signals is a topic of current debate (Chatterjee & Callaway, 2002).

scholarly journals Motion integration is anisotropic during smooth pursuit eye movements

2019 ◽  
Vol 121 (5) ◽  
pp. 1787-1797
Author(s):  
David Souto ◽  
Jayesha Chudasama ◽  
Dirk Kerzel ◽  
Alan Johnston
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Object Motion ◽  
Global Motion ◽  
Local Motion ◽  
Pursuit Eye Movements ◽  
Motion Integration ◽  
Retinal Motion ◽  
Motion Measurements

Smooth pursuit eye movements (pursuit) are used to minimize the retinal motion of moving objects. During pursuit, the pattern of motion on the retina carries not only information about the object movement but also reafferent information about the eye movement itself. The latter arises from the retinal flow of the stationary world in the direction opposite to the eye movement. To extract the global direction of motion of the tracked object and stationary world, the visual system needs to integrate ambiguous local motion measurements (i.e., the aperture problem). Unlike the tracked object, the stationary world’s global motion is entirely determined by the eye movement and thus can be approximately derived from motor commands sent to the eye (i.e., from an efference copy). Because retinal motion opposite to the eye movement is dominant during pursuit, different motion integration mechanisms might be used for retinal motion in the same direction and opposite to pursuit. To investigate motion integration during pursuit, we tested direction discrimination of a brief change in global object motion. The global motion stimulus was a circular array of small static apertures within which one-dimensional gratings moved. We found increased coherence thresholds and a qualitatively different reflexive ocular tracking for global motion opposite to pursuit. Both effects suggest reduced sampling of motion opposite to pursuit, which results in an impaired ability to extract coherence in motion signals in the reafferent direction. We suggest that anisotropic motion integration is an adaptation to asymmetric retinal motion patterns experienced during pursuit eye movements. NEW & NOTEWORTHY This study provides a new understanding of how the visual system achieves coherent perception of an object’s motion while the eyes themselves are moving. The visual system integrates local motion measurements to create a coherent percept of object motion. An analysis of perceptual judgments and reflexive eye movements to a brief change in an object’s global motion confirms that the visual and oculomotor systems pick fewer samples to extract global motion opposite to the eye movement.

Evidence for Global Motion Interactions between First-Order and Second-Order Stimuli

Perception ◽  
1998 ◽  
Vol 27 (7) ◽  
pp. 761-767 ◽  
Author(s):  
George Mather ◽  
Linda Murdoch
Keyword(s):  
Motion Analysis ◽  
Visual Motion ◽  
Global Analysis ◽  
Image Features ◽  
Second Order ◽  
The Other ◽  
Global Motion ◽  
First Order ◽  
Motion Integration ◽  
Random Block

Recent research indicates that the early stages of visual-motion analysis involve two parallel neural pathways, one conveying information from luminance-defined (first-order) image features, the other conveying information from texture-defined (second-order) features. It is still not clear whether these two pathways converge during later stages of global motion integration. According to one account they remain segregated, and feed separate global analyses. In the alternative account, all responses feed a common stage of global analysis. Two perceptual phenomena are universally held to result from interactions between detector responses during global motion integration—direction repulsion and motion capture. We conducted two psychophysical experiments on these phenomena to test for segregation of first-order and second-order responses during integration. Stimuli contained two components, either two random-block patterns transparently drifting in different directions (repulsion measurements), or a drifting square-wave grating superimposed on an incoherent random-block pattern (capture measurements). Repulsion and capture effects were measured when both stimulus components were the same order, and when one component was first order and the other was second order. Both effects were obtained for all combinations of first-order and second-order patterns. Repulsion effects were stronger with first-order inducing patterns, and capture effects were stronger with second-order inducers. The presence of perceptual interactions regardless of stimulus order strongly suggests that responses in first-order and second-order pathways interact during global motion analysis.

Global motion integration in the cat's lateral posterior-pulvinar complex

2001 ◽  
Vol 13 (12) ◽  
pp. 2218-2226 ◽  
Author(s):  
Daniela Dumbrava ◽  
Jocelyn Faubert ◽  
Christian Casanova
Keyword(s):  
Global Motion ◽  
Motion Integration ◽  
Lateral Posterior
Sign in / Sign up

Export Citation Format

Share Document