scholarly journals A superposition of moving and static stimuli appears to dilate in time when the moving stimulus is attended to

2017 ◽  
Vol 17 (10) ◽  
pp. 186
Author(s):  
Daisuke Hayashi ◽  
Hiroki Iwasawa ◽  
Takayuki Osugi ◽  
Ikuya Murakami
Keyword(s):  
Moving Stimulus

Mislocalization of the Initial and Final Position of a Moving Stimulus

2000 ◽  
Author(s):  
Jochen Musseler ◽  
Sonja Stork ◽  
Dirk Kerzel ◽  
J. Scott Jordan
Keyword(s):  
Final Position ◽  
Moving Stimulus

Servo-controlled moving stimulus generator for single unit studies in vision

1973 ◽  
Vol 13 (6) ◽  
pp. 1195-IN8 ◽  
Author(s):  
Stephen B. Leighton ◽  
Bruce M. Dow
Keyword(s):  
Single Unit ◽  
Moving Stimulus ◽  
Stimulus Generator

scholarly journals Perceived onset time and position of a moving stimulus

2003 ◽  
Vol 43 (15) ◽  
pp. 1625-1635 ◽  
Author(s):  
Kairi Kreegipuu ◽  
Jüri Allik
Keyword(s):  
Onset Time ◽  
Moving Stimulus

A new technique for estimating chromatic isoluminance in humans and monkeys

1990 ◽  
Vol 5 (6) ◽  
pp. 605-608 ◽  
Author(s):  
Avi Chaudhuri ◽  
Thomas D. Albright
Keyword(s):  
New Technique ◽  
Luminance Ratio ◽  
Optokinetic Response ◽  
Moving Stimulus ◽  
Perceptual Judgement ◽  
A New Technique ◽  
Perceived Motion

AbstractCurrent approaches to the problem of equating different colors for luminance (chromatic isoluminance) rely upon human reports of perceptual events that are reduced at some luminance ratio. In this report, a technique is described that evokes a vivid percept of motion of a textured pattern only at isoluminance. Furthermore, in both humans and monkeys, the moving stimulus produces a striking optokinetic response in the same direction as the perceived motion. If used in this manner, the technique can provide an estimate of chromatic isoluminance in a variety of species and be used to corroborate a human subjects's perceptual judgement.

scholarly journals Effect of Vergence on Human Ocular Following Response (OFR)

2009 ◽  
Vol 102 (1) ◽  
pp. 513-522 ◽  
Author(s):  
Anand C. Joshi ◽  
Matthew J. Thurtell ◽  
Mark F. Walker ◽  
Alessandro Serra ◽  
R. John Leigh
Keyword(s):  
Visual Field ◽  
Temporal Frequency ◽  
Open Loop ◽  
Motion Processing ◽  
Sinusoidal Grating ◽  
Video Monitor ◽  
Gaze Shifts ◽  
Ocular Following ◽  
Moving Stimulus ◽  
Ocular Following Response

The human ocular following response (OFR) is a preattentive, short-latency visual-field–holding mechanism, which is enhanced if the moving stimulus is applied in the wake of a saccade. Since most natural gaze shifts incorporate both saccadic and vergence components, we asked whether the OFR was also enhanced during vergence. Ten subjects viewed vertically moving sine-wave gratings on a video monitor at 45 cm that had a temporal frequency of 16.7 Hz, contrast of 32%, and spatial frequency of 0.17, 0.27, or 0.44 cycle/deg. In Fixation/OFR experiments, subjects fixed on a white central dot on the video monitor, which disappeared at the beginning of each trial, just as the sinusoidal grating started moving up or down. We measured the change in eye position in the 70- to 150-ms open-loop interval following stimulus onset. Group mean downward responses were larger (0.14°) and made at shorter latency (85 ms) than upward responses (0.10° and 96 ms). The direction of eye drifts during control trials, when gratings remained stationary, was unrelated to the prior response. During vergence/OFR experiments, subjects switched their fixation point between the white dot at 45 cm and a red spot at 15 cm, cued by the disappearance of one target and appearance of the other. When horizontal vergence velocity exceeded 15°/s, motion of sinusoidal gratings commenced and elicited the vertical OFR. Subjects showed significantly ( P < 0.001) larger OFR when the moving stimulus was presented during convergence (group mean increase of 46%) or divergence (group mean increase of 36%) compared with following fixation. Since gaze shifts between near and far are common during natural activities, we postulate that the increase of OFR during vergence movements reflects enhancement of early cortical motion processing, which serves to stabilize the visual field as the eyes approach their new fixation point.

Two-Dimensional Records Of The Eyecup Movements Of The Crab Carcinus

1969 ◽  
Vol 50 (3) ◽  
pp. 673-682
Author(s):  
W. J. P. BARNES ◽  
G. A. HORRIDGE
Keyword(s):  
Carcinus Maenas ◽  
Two Dimensions ◽  
Shore Crab ◽  
Two Dimensional ◽  
Vertical Movements ◽  
Moving Stimulus ◽  
Light Stimuli ◽  
The Common

1. The eyecup movements of the common shore crab, Carcinus maenas L., have been recorded in two dimensions. 2. Saccades and eyecup drift occur in all directions. Eyecup tremor is a complex irregular movement although horizontal tremor predominates in most crabs. 3. Although the response to the movement of the light in a circle is usually an approximate circle or ellipse, rectangular responses are occasionally obtained and the eyecup often moves in a stepwise fashion in response to a smooth diagonal movement of the light. 4. The angle of response to a diagonal movement depends on the ratio of the response to horizontal and vertical movements alone. The eye is virtually stabilized in all planes by a contrasting object but never fixates upon a moving stimulus. 5. No torsional or twisting movements of the eyecups were obtained in response to light stimuli.

Discrimination Between Movements of Eye and Object by Visual Interneurones of Crickets

1969 ◽  
Vol 50 (3) ◽  
pp. 723-732
Author(s):  
JOHN PALKA
Keyword(s):  
Eye Movement ◽  
Voluntary Movement ◽  
Compound Eye ◽  
Visual Fields ◽  
Object Motion ◽  
Visual Environment ◽  
Inhibitory Mechanism ◽  
Object Movement ◽  
Moving Stimulus ◽  
Homogeneous Environment

1. One large neurone on each side of the cervical and thoracic ventral nerve cord of crickets responds to object motion anywhere in the visual field of the ipsilateral compound eye, but not to the forced or voluntary movement of the eye itself. 2. This discrimination between self-movement and object-movement is accomplished by an inhibitory mechanism mediated by the same eye. 3. Inhibition must be present because a potent moving stimulus becomes ineffective if presented during a forced eye movement. 4. Its visual origin is demonstrated in two ways: (a) abolishing all known mechanosensory feedback does not disrupt the mechanism, but (b) alteration of visual conditions does so in a predictable way. Sweeping the eye past a complex visual environment suppresses the neurone's response to a concurrently or subsequently presented moving target, whereas the same movement past a simplified or homogeneous environment produces little or no inhibition. 5. Responses to eye movement itself are greatly enhanced in appropriately simplified visual fields, reinforcing the conclusion that the inhibition preventing response in complex fields is of visual origin. 6. Suggestive evidence for an additional inhibitory mechanism associated with voluntary movement is presented.

Speed Discrimination in Luminance and Colour Stimuli as a Function of Contrast

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 49-49
Author(s):  
S M Wuerger ◽  
A H Morgan
Keyword(s):  
Carrier Frequency ◽  
Standard Stimulus ◽  
Consistent Difference ◽  
Adaptive Procedure ◽  
Gabor Function ◽  
Moving Stimulus ◽  
Measured Speed ◽  
Speed Discrimination ◽  
Luminance Stimulus ◽  
Perceived Speed

We measured speed discrimination for isoluminant red - green and luminance-defined moving stimuli. The horizontal profile of the stimuli was a Gabor function with a carrier frequency of 2 cycles deg−1. The standard stimulus was a luminance stimulus with a fixed speed of 2 deg s−1 and a fixed contrast of 0.1. The comparison stimuli were either luminance stimuli (cone contrasts: 0.05, 0.1, 0.2, 0.4) or chromatic stimuli (cone contrasts: 0.025, 0.05, 0.1). The speed of the comparison stimuli was varied by an adaptive procedure. After each trial the observer indicated which of the 2 intervals contained the slower moving stimulus. The stimuli always moved horizontally and the direction was chosen randomly at each trial. The main findings were: (i) For luminance stimuli, the perceived speed was independent of contrast (ranging from 0.1 to 0.4). For colour stimuli, the perceived speed increased with contrast for two out of four observers. (ii) The sensitivity for speed discrimination was independent of contrast for luminance and for colour stimuli. (iii) There was no consistent difference in speed discrimination sensitivity between colour and luminance stimuli when the stimuli were equated in cone contrast.

Velocity Computation from Measures of Spatiotemporal Gradients at Multiple Orientations

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 77-77 ◽  
Author(s):  
A Johnston ◽  
P W McOwan
Keyword(s):  
Natural Extension ◽  
Image Brightness ◽  
Motion Patterns ◽  
One Dimensional ◽  
Aperture Problem ◽  
Motion Models ◽  
Temporal Domain ◽  
Moving Stimulus ◽  
Zero Values ◽  
Derivatives Of

Current models of speed and direction of motion which use measures of spatiotemporal gradients can suffer from ill-conditioning. This problem arises either because local measures of the derivatives of image brightness take zero values or because the motion equations cannot be solved for one-dimensional (1-D) signals in two-dimensional (2-D) images—the aperture problem. One way around this predicament is to select image points or introduce constants to deal with ill-conditioned calculations. Here we describe an analytic method that combines measures of speed in a range of directions to provide a well-conditioned measure of velocity at all points in the moving stimulus. This approach is a natural extension of a one-dimensional model which has been successful in predicting perceived motion in a variety of 1-D spatiotemporal motion patterns (Johnston, McOwan and Buxton 1992 Proceedings of the Royal Society of London, Series B250 297 – 306). Speed is computed with the use of biologically plausible filters that are derivatives of Gaussians in the spatial domain and log Gaussians in the temporal domain. Measures of speed and inverse speed are computed for a range of orientations consistent with the number of direction columns in MT/V5. The pattern of velocities measured over this set of orientations is then used to recover the speed and direction of motion of the stimulus. The model can correctly compute the velocity of moving 1-D patterns, such as gratings, patterns that prove a problem for many current 2-D motion models as they form degenerate cases, as well as the motion of rigid 2-D patterns.

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