Effect of Luminance Contrast on the Motion Aftereffect

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 191-191
Author(s):  
M Ishihara
Keyword(s):  
Spatial Frequency ◽  
Motion Aftereffect ◽  
Luminance Contrast ◽  
Sinusoidal Grating ◽  
Channel Activity ◽  
High Luminance ◽  
Frequency Condition ◽  
Parvocellular Pathway ◽  
Low Luminance ◽  
Transient Channel

The effects of luminance contrast and spatial frequency in the transient channel were investigated by making use of the motion aftereffect (MAE) caused by adaptation to a drifting sinusoidal grating. Two experiments were performed. The PSE of the velocity was measured as an index of the MAE. The adapting grating was made to drift at a velocity of 2.28 deg s−1 and its spatial frequency was 0.8, 1.6, or 3.2 cycles deg−1. In the first experiment, the MAE caused by a luminance contrast grating or an equiluminous chromatic grating was measured. In the second experiment, luminance contrast gratings were used to measure the effect of the contrast differences between adapting and test gratings. The largest MAE was observed when a low-luminance-contrast grating or an equiluminous chromatic grating was presented as test stimulus after adaptation to a high-luminance-contrast grating in the low-spatial-frequency condition. Generally, the MAE increased with increasing adapting contrast and with decreasing test contrast or spatial frequency. Little MAE was observed at high test contrasts. The results may be explained by assuming that activity in the sustained channel (or parvocellular pathway) inhibits activity in the transient channel (or magnocellular pathway) owing to the domination of sustained channel activity when the test is a static high-luminance-contrast grating providing much information about position and form.

Evoked Magnetic Field Elicited by Motion and Motion Aftereffect

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 113-113
Author(s):  
N Osaka ◽  
H Ashida ◽  
M Osaka ◽  
S Koyama ◽  
R Kakigi
Keyword(s):  
Magnetic Field ◽  
Spatial Frequency ◽  
Human Subject ◽  
Visual Motion ◽  
Motion Aftereffect ◽  
Sinusoidal Grating ◽  
Negative Aftereffect ◽  
Motion Condition ◽  
Clear Increase ◽  
Good Agreement

Motion aftereffect (MAE) is a negative aftereffect caused by prolonged viewing of visual motion: after gazing at a moving grating for a while, a stationary image will appear to move in the opposite direction (Ashida and Osaka, 1995 Vision Research35 1825). Evoked magnetic field (magnetoencephalogram: MEG) was measured on a human subject observing visual motion and MAE. Magnetic evoked field (80 averagings) was measured from 37 points over occipital and parietal areas (Magnes SQUID biomagnetometer, BTi) during watching a horizontally moving sinusoidal grating with low spatial frequency (2 cycles deg−1 with 5 Hz: motion condition) and immediately after stopping the moving grating (MAE condition). Dipole estimates based on equal magnetic field contour suggest that the main loci subserving visual motion and MAE appear to be the surrounding region over occipital and parietal areas in the human brain. Further analysis is now underway. In general, this appears to be in good agreement with another study using fMRI-based MAE measures [Tootell et al, 1995 Nature (London)375 139] in which a clear increase in activity in these areas was observed when subjects viewed MAE.

Resolution of binocular rivalry: Perceptual misbinding of color

2006 ◽  
Vol 23 (3-4) ◽  
pp. 561-566 ◽  
Author(s):  
SANG WOOK HONG ◽  
STEVEN K. SHEVELL
Keyword(s):  
Binocular Rivalry ◽  
Luminance Contrast ◽  
Binding Problem ◽  
High Luminance ◽  
Binding Process ◽  
Neural Representations ◽  
Low Luminance ◽  
Neural Binding ◽  
The Right

Is neural binding of color and form required for perception of a unified colored object? Individual cells selectively tuned to both color and orientation are proposed to moot the binding problem. This study reveals perceptual misbinding of color, thereby revealing separate neural representations of color and form followed by a subsequent binding process. Low luminance-contrast, rivalrous chromatic gratings were presented dichoptically. Each grating had alternating chromatic and gray stripes (e.g., red/gray in the left eye, green/gray in the right eye). Observers viewed the two rivalrous, 2 cpd gratings for 1 min. The duration of exclusive visibility was measured for four percepts: left-eye stimulus, right-eye stimulus, fusion of the two colors, or a two-color grating (e.g. a red/green grating). The percept of a two-color grating (misbinding) was observed with Michelson luminance contrast in the grating up to 20%. In general, for a given level of luminance contrast either misbinding (low luminance contrast) or color mixture (high luminance contrast) was observed, but not both of them. The perceived two-color gratings show that two rivalrous chromaticities are both represented neurally when color and form are combined to give a unified percept. “Resolution” of competing chromatic signals from the two eyes is not restricted to color dominance and color mixture. The transition from misbinding to color mixture by increasing luminance contrast shows that luminance edges have an important role in correct localization of color.

scholarly journals Different latencies of edge detection cause the fluttering-heart illusion

2021 ◽  
Author(s):  
Masahiro Suzuki ◽  
Kazuhisa Yanaka
Keyword(s):  
Edge Detection ◽  
Luminance Contrast ◽  
Second Order ◽  
High Luminance ◽  
First Order ◽  
Low Luminance

AbstractWe studied the mechanism causing the fluttering-heart illusion in which the motion of an inner figure appears unsynchronized compared with that of the outer figure surrounding it although the motion of both figures is objectively synchronized in reality. Experiment 1 examined the effect of edges’ luminance contrasts. The illusion was measured under conditions where the luminance contrasts of the outer and inner figures’ edges were varied. The results indicated that the illusion occurred when the outer figure’s edge had a high luminance contrast and the inner figure’s edge had a low luminance contrast and that the illusion was reversed when the outer figure’s edge had a low luminance contrast and the inner figure’s edge had a high luminance contrast. Experiment 2 examined the effect of the first- and second-order edges. The illusion was measured under conditions where the first- and second-order edges coexisted or only the first-order edges existed. The results indicated that the illusion occurred when the outer figure had the first-order edge and the inner figure had the second-order edge, and that the illusion was reversed when the outer figure had the second-order edge and the inner figure had the first-order edge. These findings supported the hypothesis that the different latencies of edge detection cause the fluttering-heart illusion.

Anisotropy in Oriented-Line-Target Detection at High and Low Luminance Contrast

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 38-38 ◽  
Author(s):  
L M Doherty ◽  
D H Foster
Keyword(s):  
Target Detection ◽  
Line Segment ◽  
Visual Angle ◽  
Detection Threshold ◽  
Luminance Contrast ◽  
High Luminance ◽  
Line Segments ◽  
Low Luminance ◽  
Line Target ◽  
Oriented Line

Observers can detect a uniquely oriented line segment (‘target’) in a background field of uniformly oriented line segments (‘nontargets’) even if viewing time is brief. When the lines have high luminance contrast, the variation of orientation increment threshold with nontarget orientation is periodic, generally with a period of about 90° although smaller periods have been found. Do the orientation-sensitive mechanisms giving rise to periodicities function only at high contrast? This question was addressed in a line-target detection experiment. Twenty white line segments of length 1 deg visual angle were presented in a circular field of diameter 20 deg visual angle. Nontarget orientations were in the range 0°, 5°, …, 175°, and the difference between nontarget and target orientations was varied adaptively. Stimulus displays lasting 40 ms were followed by a blank interstimulus interval lasting 60 ms and then a random-line mask. A view-tunnel provided a grey background of luminance 35 cd m−2 and stimulus contrast was 0.1, 0.3, 0.5, 0.7, or 0.9 log unit above the observer's luminance detection threshold for one line segment. When contrast was 0.1 log unit above this threshold, performance was near chance level. As contrast increased from 0.3 to 0.9 log unit above luminance detection threshold, performance improved and orientation increment thresholds decreased, showing that early orientation-processing is most effective at high luminance contrast. Nonetheless, periodicities were found in all conditions where performance was better than chance which suggests that the orientation-sensitive mechanisms associated with periodicities operate at both high and low luminance contrast.

Meridional Differences in Temporal Resolution

Perception ◽  
1982 ◽  
Vol 11 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Barry D Schwartz ◽  
Daniel K Winstead ◽  
James G May
Keyword(s):  
Spatial Frequency ◽  
Temporal Resolution ◽  
Oblique Effect ◽  
Channel Activity ◽  
Flash Duration ◽  
Choice Procedure ◽  
Stimulus Parameters ◽  
Transient Activity ◽  
Transient Channel ◽  
Forced Choice Procedure

Previous investigations of temporal resolution have shown that performance is influenced by a number of stimulus parameters. The interstimulus interval needed for accurate two-pulse discrimination has been shown to (i) decrease monotonically with flash duration, luminance, and contrast; and (ii) increase monotonically with the spatial frequency of the target. A signal-detectability two-alternative forced-choice procedure was employed to reexamine the effects of spatial frequency on temporal resolution. Also assessed was the effect of grating orientation on such performance. The results confirm that temporal resolution declines with increases in spatial frequency. Furthermore, temporal resolution was significantly lower when oblique, as opposed to vertical, grating targets were used. This ‘oblique effect’ in temporal resolution was observed only with the highest-spatial-frequency target (15 cycles deg−1), and not with stimuli of lower spatial frequency (0·9 and 3·8 cycles deg−1). These findings suggest that stimulus parameters which elicit greater transient channel activity, as opposed to sustained channel activity, enhance temporal resolution. When transient activity is at a minimum, meridional differences in temporal resolution are likely to be attributable to sustained channel activity.

Spatial frequency selective mechanisms underlying the motion aftereffect

1992 ◽  
Vol 32 (3) ◽  
pp. 561-568 ◽  
Author(s):  
E. Leslie Cameron ◽  
Curtis L. Baker ◽  
Jane C. Boulton
Keyword(s):  
Spatial Frequency ◽  
Motion Aftereffect ◽  
Frequency Selective

Spatial frequency analsis in early visual processing

1980 ◽  
Vol 290 (1038) ◽  
pp. 11-22 ◽  
Keyword(s):  
Spatial Frequency ◽  
Visual Processing ◽  
Spatial Information ◽  
Multiple Channels ◽  
Low Contrast ◽  
Local Sign ◽  
Early Visual Processing ◽  
Low Luminance ◽  
Lowered Sensitivity ◽  
Prior Adaptation

The existence of multiple channels, or multiple receptive field sizes, in the visual system does not commit us to any particular theory of spatial encoding in vision. However, distortions of apparent spatial frequency and width in a wide variety of conditions favour the idea that each channel carries a width- or frequency-related code or ‘label’ rather than a ‘local sign’ or positional label. When distortions of spatial frequency occur without prior adaptation (e.g. at low contrast or low luminance) they are associated with lowered sensitivity, and may be due to a mismatch between the perceptual labels and the actual tuning of the channels. A low-level representation of retinal space could be constructed from the spatial information encoded by the channels, rather than being projected intact from the retina.

scholarly journals The Perceived Direction of Textured Gratings and Their Motion Aftereffects

Perception ◽  
1995 ◽  
Vol 24 (12) ◽  
pp. 1383-1396 ◽  
Author(s):  
David Alais ◽  
Maarten J van der Smagt ◽  
Frans A J Verstraten ◽  
Wim A van de Grind
Keyword(s):  
Motion Aftereffect ◽  
Sine Wave ◽  
Circular Aperture ◽  
High Luminance ◽  
One Dimensional ◽  
Square Wave ◽  
Aperture Problem ◽  
Motion Energy ◽  
Motion Aftereffects ◽  
Do So

The stimuli in these experiments are square-wave luminance gratings with an array of small random dots covering the high-luminance regions. Owing to the texture, the direction of these gratings, when seen through a circular aperture, is disambiguated because the visual system is provided with an unambiguous motion energy. Thus, the direction of textured gratings can be varied independently of grating orientation. When subjects are required to judge the direction of textured gratings moving obliquely relative to their orientation, they can do so accurately (experiment 1). This is of interest because most studies of one-dimensional motion perception have involved (textureless) luminance-defined sine-wave or square-wave gratings, and the perceived direction of these gratings is constrained by the aperture problem to be orthogonal to their orientation. Thus, direction and orientation have often been confounded. Interestingly, when subjects are required to judge the direction of an obliquely moving textured grating during a period of adaptation and then the direction of the motion aftereffect (MAE) immediately following adaptation (experiments 2 and 3), these directions are not directly opposite each other. MAE directions were always more orthogonal to the orientation of the adapting grating than the corresponding direction judgments during adaptation (by as much as 25°). These results are not readily explained by conventional MAE models and possible accounts are considered.

Temporal-Discontinuity Detection with Contrast-Modulated Gratings

Perception ◽  
1995 ◽  
Vol 24 (11) ◽  
pp. 1257-1264
Author(s):  
Shigeru Ichihara ◽  
Kenji Susami
Keyword(s):  
Spatial Frequency ◽  
Modulation Frequency ◽  
Sinusoidal Grating ◽  
Local Contrast ◽  
Staircase Method ◽  
Low Contrast ◽  
Discontinuity Detection ◽  
Temporal Discontinuity ◽  
Sinusoidal Gratings ◽  
The Subject

Three experiments on temporal-discontinuity detection were carried out. In experiment 1, temporal-discontinuity thresholds were measured for sinusoidal gratings by the use of the double-staircase method. A sinusoidal grating was presented twice successively. The subject judged whether or not an interval was present. The temporal-discontinuity threshold increased as the spatial frequency of the grating increased, but decreased as the contrast of the grating increased. In experiment 2, contrast-modulated gratings were used instead of the sinusoidal grating. The temporal-discontinuity threshold increased as the carrier frequency increased, and the threshold for each contrast-modulated grating was similar to that for the no-modulation (sinusoidal) grating whose contrast was the same as the maximum local contrast of the contrast-modulated grating. In experiment 3, temporal-discontinuity thresholds were measured for low-contrast (3%) sinusoidal gratings. The thresholds were very low, even for such low-contrast gratings. These results suggest that the low-spatial-frequency channels are not involved in detecting the modulation frequency of the contrast-modulated grating. Rather, the local contrast seems to be the determinant of the detection of the contrast-modulated grating itself.

Subjective and pupil responses to discomfort glare from small, high-luminance light sources

2018 ◽  
Vol 51 (4) ◽  
pp. 592-611 ◽  
Author(s):  
Y Tyukhova ◽  
CE Waters
Keyword(s):  
Pupil Size ◽  
Rating Scale ◽  
Light Sources ◽  
Background Luminance ◽  
High Luminance ◽  
Low Luminance ◽  
Point Rating Scale ◽  
Main Effect ◽  
Discomfort Glare ◽  
Relative Change

This study examined human subjective and pupil responses to small, high-luminance light sources seen against low-luminance backgrounds. Subjective judgements of glare using a seven-point rating scale and the change in pupil diameters following exposure to glare of 47 subjects were measured during evaluation of 36 conditions comprising three glare source luminances (20,000; 205,000; 750,000 cd/m2), two source positions (0°, 10°), two source sizes (10−5, 10−4 sr) and three background luminances (0.03; 0.3; 1 cd/m2). Data analysis suggests that the relative pupil size is correlated with subjective responses to discomfort glare to some extent (r = 0.659). Analysis of variance of relative pupil size measurements demonstrates a significant main effect of the background luminance suggesting that when the background luminance decreases, the relative pupil size increases. Relative pupil size shows the same trend as the relative change in illuminance at the eyes and the discomfort glare perception.

Sign in / Sign up

Export Citation Format

Share Document