scholarly journals Stimulus Eccentricity and Spatial Frequency Interact to Determine Circular Vection

Perception ◽  
1998 ◽  
Vol 27 (9) ◽  
pp. 1067-1077 ◽  
Author(s):  
Stephen Palmisano ◽  
Barbara Gillam
Keyword(s):  
Spatial Frequency ◽  
Optic Flow ◽  
Peripheral Vision ◽  
High Spatial Frequency ◽  
Object Motion ◽  
Frequency Pattern ◽  
Circular Vection ◽  
Perception Of Self ◽  
Self Motion ◽  
Stimulus Eccentricity

While early research suggested that peripheral vision dominates the perception of self-motion, subsequent studies found little or no effect of stimulus eccentricity. In contradiction to these broad notions of ‘peripheral dominance’ and ‘eccentricity independence’, the present experiments showed that the spatial frequency of optic flow interacts with its eccentricity to determine circular vection magnitude—central stimulation producing the most compelling vection for high-spatial-frequency stimuli and peripheral stimulation producing the most compelling vection for lower-spatial-frequency stimuli. This interaction appeared to be due, in part at least, to the effect that the higher-spatial-frequency moving pattern had on subjects’ ability to organise optic flow into related motion about a single axis. For example, far-peripheral exposure to this high-spatial-frequency pattern caused many subjects to organise the optic flow into independent local regions of motion (a situation which clearly favoured the perception of object motion not self-motion). It is concluded that both high-spatial-frequency and low-spatial-frequency mechanisms are involved in the visual perception of self-motion—with their activities depending on the nature and eccentricity of the motion stimulation.

Orientation Channels in the Peripheral Visual Field

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 362-362
Author(s):  
R J Snowden
Keyword(s):  
Spatial Frequency ◽  
Peripheral Vision ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
High Spatial Frequency ◽  
Selective Adaptation ◽  
Orientation Tuning ◽  
Peripheral Retina ◽  
Foveal Vision ◽  
Analysis Techniques

Peripheral vision has been modelled as a coarser version of foveal vision. Thus visual behaviour elicited by, say, a 2 cycles deg−1 grating imaged foveally would be reproduced in the periphery by a lower spatial frequency (say 1 cycle deg−1). Tuning for orientation is broader at a low than high spatial frequency (Snowden, 1992 Vision Research32 1965 – 1974). Taken together this leads to the surprising prediction that, given a particular spatial frequency, tuning for orientation is narrower for peripheral viewing! In this study it has also been found that orientation tuning broadens with increasing temporal frequency, but the opposite relationship has been reported for peripheral vision (Sharpe and Tolhurst, 1973 Vision Research13 2103 – 2112). Orientation bandwidths were measured by the method of selective adaptation following the procedures and analysis techniques described by Snowden (1991 Proceedings of the Royal Society of London, Series B246 53 – 59). The results show that orientation bandwidths did indeed narrow as a stimulus was imaged more peripherally, so that its bandwidth in the peripheral retina could be half that of the fovea. However, at a greater eccentricity, bandwidths broadened once more. The results were not influenced by the contrast of the adaptation pattern eliminating visibility as a possible explanation. Increasing temporal frequency broadened orientation bandwidth at all eccentricities.

Dark Adaptation as a Model of the Parkinsonian Visual System

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 48-48
Author(s):  
B Wink ◽  
J P Harris
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Dark Adaptation ◽  
Peripheral Vision ◽  
Receptive Fields ◽  
High Spatial Frequency ◽  
Normal Subjects ◽  
Apparent Contrast ◽  
Contrast Gain ◽  
Spatial Frequencies

It has been suggested that the Parkinsonian visual system is like the normal visual system, but is inappropriately dark-adapted (Beaumont et al, 1987 Clinical Vision Sciences2 123 – 129). Thus it is of interest to ask to what extent dark adaptation of normal subjects produces visual changes like those of Parkinson's disease (PD). One such change is the reduction in apparent contrast of medium and high spatial frequencies in peripheral vision in the illness (Harris et al, 1992 Brain115 1447 – 1457). Normal subjects judged whether the contrast of a peripherally viewed grating was higher or lower than that of a foveally viewed grating, and a staircase technique was used to estimate the point of subjective equality. Judgements were made at four spatial frequencies (0.5 to 4.0 cycles deg−1) and four contrasts (8.0% to 64%). The display, the mean luminance of which was 26 cd m−2, was viewed through a 1.5 lu nd filter in the relatively dark-adapted condition. The ANOVA showed an interaction between dark adaptation and the spatial frequency of the gratings. Dark adaptation reduces the apparent contrast of high-spatial-frequency gratings, an effect which is greater at lower contrasts. This mimics the effect found with PD sufferers, and suggests that dark adaptation may provide a useful model of the PD visual system. In a second experiment, the effect of dark adaptation on the relationship between apparent spatial frequency in the fovea and periphery was investigated. The experiment was similar to the first, except that judgements were made about the apparent spatial frequency, rather than the contrast, of the peripheral grating. ANOVA showed no differential effect of dark adaptation on the apparent spatial frequency of the peripheral grating. This suggests that the observed reduction in apparent contrast of the peripheral gratings in dark-adapted normals and Parkinson's sufferers may reflect relative changes in contrast gain, rather than relative changes in the spatial organisation of receptive fields.

scholarly journals The A-Effect and Global Motion

Vision ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 13
Author(s):  
Pearl Guterman ◽  
Robert Allison
Keyword(s):  
Optic Flow ◽  
Object Motion ◽  
The Body ◽  
Body Tilt ◽  
Whole Body ◽  
Global Motion ◽  
Motion Direction ◽  
And Shifts ◽  
Self Motion ◽  
Gravitational Vertical

When the head is tilted, an objectively vertical line viewed in isolation is typically perceived as tilted. We explored whether this shift also occurs when viewing global motion displays perceived as either object-motion or self-motion. Observers stood and lay left side down while viewing (1) a static line, (2) a random-dot display of 2-D (planar) motion or (3) a random-dot display of 3-D (volumetric) global motion. On each trial, the line orientation or motion direction were tilted from the gravitational vertical and observers indicated whether the tilt was clockwise or counter-clockwise from the perceived vertical. Psychometric functions were fit to the data and shifts in the point of subjective verticality (PSV) were measured. When the whole body was tilted, the perceived tilt of both a static line and the direction of optic flow were biased in the direction of the body tilt, demonstrating the so-called A-effect. However, we found significantly larger shifts for the static line than volumetric global motion as well as larger shifts for volumetric displays than planar displays. The A-effect was larger when the motion was experienced as self-motion compared to when it was experienced as object-motion. Discrimination thresholds were also more precise in the self-motion compared to object-motion conditions. Different magnitude A-effects for the line and motion conditions—and for object and self-motion—may be due to differences in combining of idiotropic (body) and vestibular signals, particularly so in the case of vection which occurs despite visual-vestibular conflict.

scholarly journals Accuracy and Tuning of Flow Parsing for Visual Perception of Object Motion During Self-Motion

i-Perception ◽  
2017 ◽  
Vol 8 (3) ◽  
pp. 204166951770820 ◽  
Author(s):  
Diederick C. Niehorster ◽  
Li Li
Keyword(s):  
Visual Perception ◽  
Optic Flow ◽  
Visual Information ◽  
Computational Models ◽  
Object Motion ◽  
Local Motion ◽  
Retinal Motion ◽  
Accurate Perception ◽  
Motion Speed ◽  
Self Motion

How do we perceive object motion during self-motion using visual information alone? Previous studies have reported that the visual system can use optic flow to identify and globally subtract the retinal motion component resulting from self-motion to recover scene-relative object motion, a process called flow parsing. In this article, we developed a retinal motion nulling method to directly measure and quantify the magnitude of flow parsing (i.e., flow parsing gain) in various scenarios to examine the accuracy and tuning of flow parsing for the visual perception of object motion during self-motion. We found that flow parsing gains were below unity for all displays in all experiments; and that increasing self-motion and object motion speed did not alter flow parsing gain. We conclude that visual information alone is not sufficient for the accurate perception of scene-relative motion during self-motion. Although flow parsing performs global subtraction, its accuracy also depends on local motion information in the retinal vicinity of the moving object. Furthermore, the flow parsing gain was constant across common self-motion or object motion speeds. These results can be used to inform and validate computational models of flow parsing.

scholarly journals Acoustic facilitation of object movement detection during self-motion

2011 ◽  
Vol 278 (1719) ◽  
pp. 2840-2847 ◽  
Author(s):  
F. J. Calabro ◽  
S. Soto-Faraco ◽  
L. M. Vaina
Keyword(s):  
Optic Flow ◽  
Animal Species ◽  
Moving Objects ◽  
Object Motion ◽  
Auditory Stimuli ◽  
Object Representations ◽  
Detection Rates ◽  
Object Movement ◽  
Psychophysical Studies ◽  
Self Motion

In humans, as well as most animal species, perception of object motion is critical to successful interaction with the surrounding environment. Yet, as the observer also moves, the retinal projections of the various motion components add to each other and extracting accurate object motion becomes computationally challenging. Recent psychophysical studies have demonstrated that observers use a flow-parsing mechanism to estimate and subtract self-motion from the optic flow field. We investigated whether concurrent acoustic cues for motion can facilitate visual flow parsing, thereby enhancing the detection of moving objects during simulated self-motion. Participants identified an object (the target) that moved either forward or backward within a visual scene containing nine identical textured objects simulating forward observer translation. We found that spatially co-localized, directionally congruent, moving auditory stimuli enhanced object motion detection. Interestingly, subjects who performed poorly on the visual-only task benefited more from the addition of moving auditory stimuli. When auditory stimuli were not co-localized to the visual target, improvements in detection rates were weak. Taken together, these results suggest that parsing object motion from self-motion-induced optic flow can operate on multisensory object representations.

scholarly journals Differential effects of reduced contrast on perception of self-motion vs. object-motion

2013 ◽  
Vol 13 (9) ◽  
pp. 949-949
Author(s):  
D. A. Owens ◽  
J. Gu ◽  
R. Patterson
Keyword(s):  
Object Motion ◽  
Differential Effects ◽  
Perception Of Self ◽  
Self Motion

Directional preponderance in pitch circular vection

2000 ◽  
Vol 10 (2) ◽  
pp. 93-98
Author(s):  
H. Fushiki ◽  
S. Takata ◽  
K. Yasuda ◽  
Y. Watanabe
Keyword(s):  
Stimulus Presentation ◽  
Vertical Axis ◽  
Directional Asymmetry ◽  
Stripe Pattern ◽  
Circular Vection ◽  
Significant Difference ◽  
Perception Of Self ◽  
Self Motion ◽  
Random Dot Pattern ◽  
Rotational Stimulation

We used optokinetic stimulation (OKS) in eighteen normal adults aged 18–30 years to investigate vertical self-motion perception. In order to induce self-rotation, either a stripe pattern or a random dot pattern was projected onto the inner wall of a hemispherical dome with a diameter of 150 cm. The pattern was rotated either about the subject’s vertical axis (yaw) or about the subject’s interaural axis (pitch) for 80 s at a constant acceleration of 1 deg / s 2 . Stimuli were randomly repeated three to four times in each direction. The latency of onset as well as the perceived intensity of circular vection (CV) was measured for each stimulus presentation. CV latencies for upward rotational stimulation were significantly longer than those for downward rotational stimulation under both types of stimulus conditions. There was no significant difference in CV latency between rightward and leftward rotational stimulation. For most subjects, the magnitudes of the perceived CV for rightward rotational stimulation were equal to those for leftward rotational stimulation, whereas the magnitudes of the perceived CV for vertical stimulation showed large intersubject variability. These results provide additional evidence that fundamental differences exist between different types of self-motion. Possible explanations for the directional asymmetry in vertical perception of self-motion will also be discussed.

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