Local and Global Representations of Velocity: Transparency, Opponency, and Global Direction Perception

Perception ◽  
1997 ◽  
Vol 26 (8) ◽  
pp. 995-1010 ◽  
Author(s):  
Oliver Braddick
Keyword(s):  
Visual Motion ◽  
Multiple Scales ◽  
Human Subjects ◽  
Motion Processing ◽  
Spatial Integration ◽  
Local Motion ◽  
Directional Information ◽  
Object Based ◽  
Transparent Display ◽  
Winner Take All

Human subjects can perceive global motion or motions in displays containing diverse local motions, implying representation of velocity at multiple scales. The phenomena of flexible global direction judgments, and especially of motion transparency, also raise the issue of whether the representation of velocity at any one scale is single-valued or multi-valued. A new performance-based measure of transparency confirms that the visual system represents directional information for each component of a transparent display. However, results with the locally paired random-dot display introduced by Qian et al, show that representations of multiple velocities do not coexist at the finest spatial scale of motion analysis. Functionally distinct scales of motion processing may be associated with (i) local motion detectors which show a strong winner-take-all interaction; (ii) spatial integration of local signals to disambiguate velocity; (iii) selection of reliable velocity signals as proposed in the model of Nowlan and Sejnowski; (iv) object-based or surface-based representations that are not necessarily organised in a fixed spatial matrix. These possibilities are discussed in relation to the neurobiological organisation of the visual motion pathway.

scholarly journals Computing motion in the primate's visual system

1989 ◽  
Vol 146 (1) ◽  
pp. 115-139
Author(s):  
C. Koch ◽  
H. T. Wang ◽  
B. Mathur
Keyword(s):  
Flow Field ◽  
Visual System ◽  
Optical Flow ◽  
Visual Motion ◽  
Population Coding ◽  
Spatial Integration ◽  
Local Motion ◽  
Temporal Area ◽  
Second Stage ◽  
Optical Flow Field

Computing motion on the basis of the time-varying image intensity is a difficult problem for both artificial and biological vision systems. We will show how one well-known gradient-based computer algorithm for estimating visual motion can be implemented within the primate's visual system. This relaxation algorithm computes the optical flow field by minimizing a variational functional of a form commonly encountered in early vision, and is performed in two steps. In the first stage, local motion is computed, while in the second stage spatial integration occurs. Neurons in the second stage represent the optical flow field via a population-coding scheme, such that the vector sum of all neurons at each location codes for the direction and magnitude of the velocity at that location. The resulting network maps onto the magnocellular pathway of the primate visual system, in particular onto cells in the primary visual cortex (V1) as well as onto cells in the middle temporal area (MT). Our algorithm mimics a number of psychophysical phenomena and illusions (perception of coherent plaids, motion capture, motion coherence) as well as electrophysiological recordings. Thus, a single unifying principle ‘the final optical flow should be as smooth as possible’ (except at isolated motion discontinuities) explains a large number of phenomena and links single-cell behavior with perception and computational theory.

Eye Movements in Response to Dichoptic Motion: Evidence for a Parallel-Hierarchical Structure of Visual Motion Processing in Primates

2008 ◽  
Vol 99 (5) ◽  
pp. 2329-2346 ◽  
Author(s):  
Ryusuke Hayashi ◽  
Kenichiro Miura ◽  
Hiromitsu Tabata ◽  
Kenji Kawano
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Large Field ◽  
Motion Processing ◽  
Motion Cues ◽  
First Order ◽  
Visual Motion Processing ◽  
Ocular Following ◽  
Winner Take All ◽  
Take All

Brief movements of a large-field visual stimulus elicit short-latency tracking eye movements termed “ocular following responses” (OFRs). To address the question of whether OFRs can be elicited by purely binocular motion signals in the absence of monocular motion cues, we measured OFRs from monkeys using dichoptic motion stimuli, the monocular inputs of which were flickering gratings in spatiotemporal quadrature, and compared them with OFRs to standard motion stimuli including monocular motion cues. Dichoptic motion did elicit OFRs, although with longer latencies and smaller amplitudes. In contrast to these findings, we observed that other types of motion stimuli categorized as non-first-order motion, which is undetectable by detectors for standard luminance-defined (first-order) motion, did not elicit OFRs, although they did evoke the sensation of motion. These results indicate that OFRs can be driven solely by cortical visual motion processing after binocular integration, which is distinct from the process incorporating non-first-order motion for elaborated motion perception. To explore the nature of dichoptic motion processing in terms of interaction with monocular motion processing, we further recorded OFRs from both humans and monkeys using our novel motion stimuli, the monocular and dichoptic motion signals of which move in opposite directions with a variable motion intensity ratio. We found that monocular and dichoptic motion signals are processed in parallel to elicit OFRs, rather than suppressing each other in a winner-take-all fashion, and the results were consistent across the species.

Center-Surround Interactions in the Middle Temporal Visual Area of the Owl Monkey

2000 ◽  
Vol 84 (5) ◽  
pp. 2658-2669 ◽  
Author(s):  
Richard T. Born
Keyword(s):  
Visual Motion ◽  
Receptive Fields ◽  
Visual Area ◽  
Motion Processing ◽  
Wide Field ◽  
Local Motion ◽  
Middle Temporal ◽  
Visual Motion Processing ◽  
Owl Monkey ◽  
Motion Contrast

Microelectrode recording and 2-deoxyglucose (2dg) labeling were used to investigate center-surround interactions in the middle temporal visual area (MT) of the owl monkey. These techniques revealed columnar groups of neurons whose receptive fields had opposite types of center-surround interaction with respect to moving visual stimuli. In one type of column, neurons responded well to objects such as a single bar or spot but poorly to large textured stimuli such as random dots. This was often due to the fact that the receptive fields had antagonistic surrounds: surround motion in the same direction as that preferred by the center suppressed responses, thus rendering these neurons unresponsive to wide-field motion. In the second set of complementary, interdigitated columns, neuronal receptive fields had reinforcing surrounds and responded optimally to wide-field motion. This functional organization could not be accounted for by systematic differences in binocular disparity. Within both column types, neurons whose receptive fields exhibited center-surround interactions were found less frequently in the input layers compared with the other layers. Additional tests were done on single units to examine the nature of the center-surround interactions. The direction tuning of the surround was broader than that of the center, and the preferred direction, with respect to that of the center, tended to be either in the same or opposite direction and only rarely in orthogonal directions. Surround motion at various velocities modulated the overall responsiveness to centrally placed moving stimuli, but it did not produce shifts in the peaks of the center's tuning curves for either direction or speed. In layers 3B and 5 of the local motion processing columns, a number of neurons responded only to local motion contrast but did so over a region of the visual field that was much larger than the optimal stimulus size. The central feature of this receptive field type was the generalization of surround antagonism over retinotopic space—a property similar to other “complex” receptive fields described previously. The columnar organization of different types of center-surround interactions may reflect the initial segregation of visual motion information into wide-field and local motion contrast systems that serve complementary functions in visual motion processing. Such segregation appears to occur at later stages of the macaque motion processing stream, in the medial superior temporal area (MST), and has also been described in invertebrate visual systems where it appears to be involved in the important function of distinguishing background motion from object motion.

scholarly journals Comparing the influence of stimulus size and contrast on the perception of moving gratings and random dot patterns—A registered report protocol

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253067
Author(s):  
Benedict Wild ◽  
Stefan Treue
Keyword(s):  
Motion Perception ◽  
Visual Motion ◽  
Human Subjects ◽  
Motion Processing ◽  
Temporal Area ◽  
Middle Temporal ◽  
Processing Pipeline ◽  
Visual Motion Processing ◽  
Primate Brain ◽  
Random Dot Patterns

Modern accounts of visual motion processing in the primate brain emphasize a hierarchy of different regions within the dorsal visual pathway, especially primary visual cortex (V1) and the middle temporal area (MT). However, recent studies have called the idea of a processing pipeline with fixed contributions to motion perception from each area into doubt. Instead, the role that each area plays appears to depend on properties of the stimulus as well as perceptual history. We propose to test this hypothesis in human subjects by comparing motion perception of two commonly used stimulus types: drifting sinusoidal gratings (DSGs) and random dot patterns (RDPs). To avoid potential biases in our approach we are pre-registering our study. We will compare the effects of size and contrast levels on the perception of the direction of motion for DSGs and RDPs. In addition, based on intriguing results in a pilot study, we will also explore the effects of a post-stimulus mask. Our approach will offer valuable insights into how motion is processed by the visual system and guide further behavioral and neurophysiological research.

Motion Perception: From Detection to Interpretation

2018 ◽  
Vol 4 (1) ◽  
pp. 501-523 ◽  
Author(s):  
Shin'ya Nishida ◽  
Takahiro Kawabe ◽  
Masataka Sawayama ◽  
Taiki Fukiage
Keyword(s):  
Motion Perception ◽  
Visual Motion ◽  
Specular Reflection ◽  
Motion Vector ◽  
Motion Processing ◽  
Local Motion ◽  
Computational Framework ◽  
Motion Signal ◽  
Visual Motion Processing ◽  
Level Of Processing

Visual motion processing can be conceptually divided into two levels. In the lower level, local motion signals are detected by spatiotemporal-frequency-selective sensors and then integrated into a motion vector flow. Although the model based on V1-MT physiology provides a good computational framework for this level of processing, it needs to be updated to fully explain psychophysical findings about motion perception, including complex motion signal interactions in the spatiotemporal-frequency and space domains. In the higher level, the velocity map is interpreted. Although there are many motion interpretation processes, we highlight the recent progress in research on the perception of material (e.g., specular reflection, liquid viscosity) and on animacy perception. We then consider possible linking mechanisms of the two levels and propose intrinsic flow decomposition as the key problem. To provide insights into computational mechanisms of motion perception, in addition to psychophysics and neurosciences, we review machine vision studies seeking to solve similar problems.

Extrapolation of Visual Motion for Manual Interception

2008 ◽  
Vol 99 (6) ◽  
pp. 2956-2967 ◽  
Author(s):  
John F. Soechting ◽  
Martha Flanders
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Hand Movement ◽  
Target Motion ◽  
Target Color ◽  
Local Motion ◽  
Initial Direction ◽  
Time Required ◽  
Starting Location ◽  
The Right

A frequent goal of hand movement is to touch a moving target or to make contact with a stationary object that is in motion relative to the moving head and body. This process requires a prediction of the target's motion, since the initial direction of the hand movement anticipates target motion. This experiment was designed to define the visual motion parameters that are incorporated in this prediction of target motion. On seeing a go signal (a change in target color), human subjects slid the right index finger along a touch-sensitive computer monitor to intercept a target moving along an unseen circular or oval path. The analysis focused on the initial direction of the interception movement, which was found to be influenced by the time required to intercept the target and the target's distance from the finger's starting location. Initial direction also depended on the curvature of the target's trajectory in a manner that suggested that this parameter was underestimated during the process of extrapolation. The pattern of smooth pursuit eye movements suggests that the extrapolation of visual target motion was based on local motion cues around the time of the onset of hand movement, rather than on a cognitive synthesis of the target's pattern of motion.

Perceptual, Oculomotor, and Neural Responses to Moving Color Plaids

Perception ◽  
1998 ◽  
Vol 27 (6) ◽  
pp. 681-709 ◽  
Author(s):  
Karen R Dobkins ◽  
Gene R Stoner ◽  
Thomas D Albright
Keyword(s):  
Eye Movements ◽  
Visual Motion ◽  
Human Subjects ◽  
Phase Relationship ◽  
Neural Mechanism ◽  
Luminance Contrast ◽  
Motion Processing ◽  
Motion Coherence ◽  
Bright Green ◽  
Phase Relationships

Moving plaids constructed from two achromatic gratings of identical luminance contrast are known to yield a percept of coherent pattern motion, as are plaids constructed from two identical chromatic (eg isoluminant red/green) gratings. To examine the interactive influences of chromatic and luminance contrast on the integration of visual motion signals, we constructed plaids with gratings that possessed both forms of contrast. We used plaids of two basic types, which differed with respect to the phase relationship between chromatic and luminance modulations (after Kooi et al, 1992 Perception21 583–598). One plaid type (‘symmetric’) was made from component gratings that had identical chromatic/luminance phase relationships (eg both components were red-bright/green-dark modulation). The second plaid type (‘asymmetric’) was made from components that had complimentary phase relationships (ie one red-bright/green-dark grating and one green-bright/red-dark grating). Human subjects reported that the motion of symmetric plaids was perceptually coherent, while the components of asymmetric plaids failed to cohere. We also recorded eye movements elicited by both types of plaids to determine if they are similarly affected by these image cues for motion coherence. Results demonstrate that, under many conditions, eye movements elicited by perceptually coherent vs noncoherent plaids are distinguishable from one another. To reveal the neural bases of these perceptual and oculomotor phenomena, we also recorded the responses of neurons in the middle temporal visual area (area MT) of macaque visual cortex. Here we found that individual neurons exhibited differential tuning to symmetric vs asymmetric plaids. These neurophysiological results demonstrate that the neural mechanism for motion coherence is sensitive to the phase relationship between chromatic and luminance contrast, a finding which has implications for interactions between ‘color’ and ‘motion’ processing streams in the primate visual system.

scholarly journals Self-operated stimuli improve subsequent visual motion processing

2020 ◽  
Author(s):  
Giulia Sedda ◽  
David J. Ostry ◽  
Vittorio Sanguineti ◽  
Silvio P. Sabatini
Keyword(s):  
Visual Information ◽  
Visual Motion ◽  
Internal Representation ◽  
Fine Tuning ◽  
Motion Processing ◽  
Stimulus Motion ◽  
Directional Information ◽  
Movement Training ◽  
Visual Motion Processing ◽  
Perceptual Changes

Proper interpretation of visual information requires capturing the structural regularities in the visual signal and this frequently occurs in conjunction with movement. Perceptual interpretation is complicated both by transient perceptual changes that accompany motor activity, and as found in audition and somatosensation, by more persistent changes that accompany the learning of new movements. Here we asked whether motor learning also results in sustained changes to visual perception. We designed a reaching task in which participants directly controlled the visual information they received, which we term self-operated stimuli. Specifically, they trained to make movements in a number of directions. Directional information was provided by the motion of an intrinsically ambiguous moving stimulus which was directly tied to motion of the hand. We find that movement training improves perception of coherent stimulus motion, and that changes in movement are correlated with the perceptual change. No perceptual changes are observed in passive observers even when they are provided with an explicit strategy to solve perceptual grouping. Comparison of empirical perceptual data with simulations based on a Bayesian generative model of motion perception suggests that movement training promotes the fine-tuning of the internal representation of stimulus geometry. These results emphasize the role of sensorimotor interaction in determining the persistent properties in space and time that define a percept.

Sign in / Sign up

Export Citation Format

Share Document