scholarly journals Dynamic illusory size contrast: A relative-size illusion modulated by stimulus motion and eye movements

2014 ◽  
Vol 14 (3) ◽  
pp. 2-2 ◽  
Author(s):  
R. E. B. Mruczek ◽  
C. D. Blair ◽  
G. P. Caplovitz
Keyword(s):  
Eye Movements ◽  
Relative Size ◽  
Stimulus Motion ◽  
Size Contrast

scholarly journals Dynamic Illusory Size-Contrast: A relative-size illusion modulated by stimulus motion and eye movements

2014 ◽  
Vol 14 (10) ◽  
pp. 890-890
Author(s):  
R. Mruczek ◽  
C. Blair ◽  
G. Caplovitz
Keyword(s):  
Eye Movements ◽  
Relative Size ◽  
Stimulus Motion ◽  
Size Contrast

Vision without Contours: Study of Visual Information from Ordinal Stimulation

1968 ◽  
Vol 26 (2) ◽  
pp. 335-351 ◽  
Author(s):  
Gunnar Johansson
Keyword(s):  
Eye Movements ◽  
Visual Information ◽  
Sensitivity Threshold ◽  
Continuous Change ◽  
Stimulus Motion ◽  
Pursuit Eye Movements ◽  
Illuminance Level ◽  
Sinusoidal Pattern ◽  
Moving Pattern ◽  
Sinusoidal Function

Continuous change of illuminance over retinal area in accordance with the sinusoidal function was studied as a stimulus for the human visual system. Its efficiency in controlling pursuit eye movements was compared with that of a stepwise luminance function (square wave). Such distributions of luminance were generated on a cathode ray screen (wavelength at the eye 9° and 3°) and were given a small translatory motion (2° – 12′). Ss were instructed to follow the moving pattern with pursuit eye movements. There is no difference in performance between the two types of brightness distributions. A stimulus motion of 24′ was sufficient to produce full evidence of eye tracking in all Ss also from the contour-free sinusoidal pattern. This means that the brightness change in every point of the CRT screen was far below the retinal sensitivity threshold at the illuminance level used. Thus a summation effect occurs. This was taken as a support for an hypothesis about “ordinal” stimulation. Arguments from modern neurophysiology are introduced and yield further support for the conclusion.

Visual responses of pulvinar and collicular neurons during eye movements of awake, trained macaques

1991 ◽  
Vol 66 (2) ◽  
pp. 485-496 ◽  
Author(s):  
D. L. Robinson ◽  
J. W. McClurkin ◽  
C. Kertzman ◽  
S. E. Petersen
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Stimulus Movement ◽  
Pursuit Eye Movements ◽  
Extraretinal Signal ◽  
Wide Range

1. We recorded from single neurons in awake, trained rhesus monkeys in a lighted environment and compared responses to stimulus movement during periods of fixation with those to motion caused by saccadic or pursuit eye movements. Neurons in the inferior pulvinar (PI), lateral pulvinar (PL), and superior colliculus were tested. 2. Cells in PI and PL respond to stimulus movement over a wide range of speeds. Some of these cells do not respond to comparable stimulus motion, or discharge only weakly, when it is generated by saccadic or pursuit eye movements. Other neurons respond equivalently to both types of motion. Cells in the superficial layers of the superior colliculus have similar properties to those in PI and PL. 3. When tested in the dark to reduce visual stimulation from the background, cells in PI and PL still do not respond to motion generated by eye movements. Some of these cells have a suppression of activity after saccadic eye movements made in total darkness. These data suggest that an extraretinal signal suppresses responses to visual stimuli during eye movements. 4. The suppression of responses to stimuli during eye movements is not an absolute effect. Images brighter than 2.0 log units above background illumination evoke responses from cells in PI and PL. The suppression appears stronger in the superior colliculus than in PI and PL. 5. These experiments demonstrate that many cells in PI and PL have a suppression of their responses to stimuli that cross their receptive fields during eye movements. These cells are probably suppressed by an extraretinal signal. Comparable effects are present in the superficial layers of the superior colliculus. These properties in PI and PL may reflect the function of the ascending tectopulvinar system.

Dynamic Illusory Size Contrast

2017 ◽  
Author(s):  
Ryan E. B. Mruczek ◽  
D. Blair Christopher ◽  
Lars Strother ◽  
Gideon P. Caplovitz
Keyword(s):  
Eye Movements ◽  
Retinal Image ◽  
Target Motion ◽  
Moving Object ◽  
Size Change ◽  
Central Target ◽  
Powerful Effect ◽  
Size Contrast

Static size contrast and assimilation illusions, such as the Ebbinghaus and Delboeuf illusions, show that the size of nearby objects in a scene can influence the perceived size of a central target. This chapter describes a dynamic variant of these classic size illusions, called the Dynamic Illusory Size-Contrast (DISC) effect. In the DISC effect, a surrounding stimulus that continuously changes size causes an illusory size change in a central target. The effect is dramatically enhanced in the presence of additional stimulus dynamics arising from eye movements or target motion. The chapter proposes that this surprisingly powerful effect of motion on perceived size depends on the degree of uncertainty inherent in the size of the retinal image of a moving object.

Relative size of numerical magnitude induces a size-contrast effect on the grip scaling of reach-to-grasp movements

Cortex ◽  
2012 ◽  
Vol 48 (8) ◽  
pp. 1043-1051 ◽  
Author(s):  
Rocco Y.-C. Chiou ◽  
Denise H. Wu ◽  
Ovid J.-L. Tzeng ◽  
Daisy L. Hung ◽  
Erik C. Chang
Keyword(s):  
Contrast Effect ◽  
Relative Size ◽  
Numerical Magnitude ◽  
Reach To Grasp ◽  
Size Contrast

Visual Responses of the Human Superior Colliculus: A High-Resolution Functional Magnetic Resonance Imaging Study

2005 ◽  
Vol 94 (4) ◽  
pp. 2491-2503 ◽  
Author(s):  
Keith A. Schneider ◽  
Sabine Kastner
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
High Resolution ◽  
Superior Colliculus ◽  
Visual Fields ◽  
Visual Response ◽  
Visual Responses ◽  
Subcortical Structures ◽  
Stimulus Motion ◽  
Low Contrast

The superior colliculus (SC) is a multimodal laminar structure located on the roof of the brain stem. The SC is a key structure in a distributed network of areas that mediate saccadic eye movements and shifts of attention across the visual field and has been extensively studied in nonhuman primates. In humans, it has proven difficult to study the SC with functional MRI (fMRI) because of its small size, deep location, and proximity to pulsating vascular structures. Here, we performed a series of high-resolution fMRI studies at 3 T to investigate basic visual response properties of the SC. The retinotopic organization of the SC was determined using the traveling wave method with flickering checkerboard stimuli presented at different polar angles and eccentricities. SC activations were confined to stimulation of the contralateral hemifield. Although a detailed retinotopic map was not observed, across subjects, the upper and lower visual fields were represented medially and laterally, respectively. Responses were dominantly evoked by stimuli presented along the horizontal meridian of the visual field. We also measured the sensitivity of the SC to luminance contrast, which has not been previously reported in primates. SC responses were nearly saturated by low contrast stimuli and showed only small response modulation with higher contrast stimuli, indicating high sensitivity to stimulus contrast. Responsiveness to stimulus motion in the SC was shown by robust activations evoked by moving versus static dot stimuli that could not be attributed to eye movements. The responses to contrast and motion stimuli were compared with those in the human lateral geniculate nucleus. Our results provide first insights into basic visual responses of the human SC and show the feasibility of studying subcortical structures using high-resolution fMRI.

scholarly journals Dramatic changes to well-known places go unnoticed

2020 ◽  
Author(s):  
R. Shayna Rosenbaum ◽  
Julia G. Halilova ◽  
Sabrina Agnihotri ◽  
Maria C. D'Angelo ◽  
Gordon Winocur ◽  
...  
Keyword(s):  
Eye Movements ◽  
Eye Tracking ◽  
Declarative Memory ◽  
Relative Size ◽  
Visual Exploration ◽  
Spatial Context ◽  
Extensive Experience ◽  
Indirect Measure ◽  
Fine Grained

How well do we know our city? It turns out, much more poorly than we might imagine. We used declarative memory and eye-tracking techniques to examine people’s ability to detect modifications of landmarks in Toronto locales with which they have had extensive experience. Participants were poor at identifying which scenes contained altered landmarks, whether the modification was to the landmarks’ relative size, internal features, or surrounding context. To determine whether an indirect measure would prove more sensitive, we tracked eye movements during viewing. Changes in overall visual exploration, but not to specific regions of change, were related to participants’ explicit endorsement of scenes as modified. These results support the contention that very familiar landmarks are strongly integrated within the spatial context in which they were first experienced, so that any changes that are consciously detected are at a global or coarse, but not local or fine-grained, level.

Visuomotor properties of corticotectal cells in area 17 and posteromedial lateral suprasylvian (PMLS) cortex of the cat

2001 ◽  
Vol 18 (1) ◽  
pp. 77-91 ◽  
Author(s):  
THEODORE G. WEYAND ◽  
ADELE C. GAFKA
Keyword(s):  
Eye Movements ◽  
Oculomotor System ◽  
Oscillatory Activity ◽  
Visual Response ◽  
Area 17 ◽  
Stimulus Motion ◽  
Velocity Amplitude ◽  
Cortical Areas ◽  
Saccade Velocity ◽  
Visual Cortical

We studied the visuomotor activity of corticotectal (CT) cells in two visual cortical areas [area 17 and the posteromedial lateral suprasylvian cortex (PMLS)] of the cat. The cats were trained in simple oculomotor tasks, and head position was fixed. Most CT cells in both cortical areas gave a vigorous discharge to a small stimulus used to control gaze when it fell within the retinotopically defined visual field. However, the vigor of the visual response did not predict latency to initiate a saccade, saccade velocity, amplitude, or even if a saccade would be made, minimizing any potential role these cells might have in premotor or attentional processes. Most CT cells in both areas were selective for direction of stimulus motion, and cells in PMLS showed a direction preference favoring motion away from points of central gaze. CT cells did not discharge with eye movements in the dark. During eye movements in the light, many CT cells in area 17 increased their activity. In contrast, cells in PMLS, including CT cells, were generally unresponsive during saccades. Paradoxically, cells in PMLS responded vigorously to stimuli moving at saccadic velocities, indicating that the oculomotor system suppresses visual activity elicited by moving the retina across an illuminated scene. Nearly all CT cells showed oscillatory activity in the frequency range of 20–90 Hz, especially in response to visual stimuli. However, this activity was capricious; strong oscillations in one trial could disappear in the next despite identical stimulus conditions. Although the CT cells in both of these regions share many characteristics, the direction anisotropy and the suppression of activity during eye movements which characterize the neurons in PMLS suggests that these two areas have different roles in facilitating perceptual/motor processes at the level of the superior colliculus.

scholarly journals Spatial summation in the human fovea: the effect of optical aberrations and fixational eye movements

2018 ◽  
Author(s):  
William S. Tuten ◽  
Robert F. Cooper ◽  
Pavan Tiruveedhula ◽  
Alfredo Dubra ◽  
Austin Roorda ◽  
...  
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Adaptive Optics ◽  
Ganglion Cells ◽  
Spatial Summation ◽  
Spatial Vision ◽  
Optical Aberrations ◽  
Stimulus Motion ◽  
Fixational Eye Movements ◽  
Magnocellular Visual Pathway

AbstractPsychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these pre-neural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco’s area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by post-receptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single post-receptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco’s area in the central fovea.

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