scholarly journals Measuring the role of chromatic saturation and luminance contrast in color spreading using hue cancellation

2002 ◽  
Vol 2 (10) ◽  
pp. 25-25 ◽  
Author(s):  
W. Davis ◽  
K. K. Valois
Keyword(s):  
Luminance Contrast ◽  
Color Spreading ◽  
Hue Cancellation

How a Brain Sees: Constructing Reality

2021 ◽  
pp. 86-121
Author(s):  
Stephen Grossberg
Keyword(s):  
Visual Arts ◽  
Explanatory Power ◽  
General Purpose ◽  
Image Features ◽  
Color Spreading ◽  
New Concepts ◽  
Artistic Styles ◽  
Neon Color Spreading ◽  
Boundary Completion

The distinction between seeing and knowing, and why our brains even bother to see, are discussed using vivid perceptual examples, including image features without visible qualia that can nonetheless be consciously recognized, The work of Helmholtz and Kanizsa exemplify these issues, including examples of the paradoxical facts that “all boundaries are invisible”, and that brighter objects look closer. Why we do not see the big holes in, and occluders of, our retinas that block light from reaching our photoreceptors is explained, leading to the realization that essentially all percepts are visual illusions. Why they often look real is also explained. The computationally complementary properties of boundary completion and surface filling-in are introduced and their unifying explanatory power is illustrated, including that “all conscious qualia are surface percepts”. Neon color spreading provides a vivid example, as do self-luminous, glary, and glossy percepts. How brains embody general-purpose self-organizing architectures for solving modal problems, more general than AI algorithms, but less general than digital computers, is described. New concepts and mechanisms of such architectures are explained, including hierarchical resolution of uncertainty. Examples from the visual arts and technology are described to illustrate them, including paintings of Baer, Banksy, Bleckner, da Vinci, Gene Davis, Hawthorne, Hensche, Matisse, Monet, Olitski, Seurat, and Stella. Paintings by different artists and artistic schools instinctively emphasize some brain processes over others. These choices exemplify their artistic styles. The role of perspective, T-junctions, and end gaps are used to explain how 2D pictures can induce percepts of 3D scenes.

Reduced Cognitive Control of a Visually Bistable Image in Schizophrenia

2011 ◽  
Vol 17 (3) ◽  
pp. 551-556 ◽  
Author(s):  
Ryan McBain ◽  
Daniel J. Norton ◽  
Jejoong Kim ◽  
Yue Chen
Keyword(s):  
Cognitive Control ◽  
Sensory Input ◽  
Necker Cube ◽  
Cognitive Remediation ◽  
Luminance Contrast ◽  
Contrast Condition ◽  
Cube Plane ◽  
Sensory Features ◽  
Visual Modulation

AbstractSchizophrenia is associated with the inability to control and coordinate thoughts, actions, and perceptions. In conventional assessments of cognitive control, multiple sensory features of stimuli are concomitantly manipulated, introducing a confounding role of bottom-up perceptual information. To overcome this difficulty, we used an ambiguous visual stimulus (Necker cube), which allowed measurement of cognitive control with constant sensory input. Subjects (20 patients, 20 controls) were asked to control their perception of a transparent Necker cube by keeping a designated plane at the front or back of the stimulus, the position of which is perceptually bistable. Patients were highly deficient at controlling their perception of the cube. When a visual feature (the luminance contrast between a designated cube plane and the other planes) was systematically manipulated, an interaction was found whereby schizophrenia patients no longer under-performed on the highest contrast condition. These results show patients’ impairment of controlling perception in the absence of visual modulation and suggest the potential utility of perceptually based approaches to cognitive remediation in schizophrenia. (JINS, 2011, 551–556)

Geometrical Errors Are the Cost of Maintaining the Luminance Contrast Polarity

2017 ◽  
Author(s):  
Sergio Roncato
Keyword(s):  
Luminance Contrast ◽  
Contrast Polarity ◽  
Geometrical Errors ◽  
Visual Completion ◽  
Visual Organization ◽  
Preferential Rule ◽  
The Cost

The visual completion is the result of the integration of fragmented contours. The contrast polarity (or contrast sign) may affect this interpolation by strengthening the completion in a direction where the contrast polarity is preserved. This chapter illustrates some manifestations of these phenomena: the alteration of the alignment of the visual units and the illusory tilt of more complex visual organization. The occurrence of basic distorting effects underlying classic illusions—such as the Frazer illusion—is discussed. It is noted that the role of the contrast polarity rule in representing a “preferential” rule does not preclude other possibilities, such as edges completion, although it renders the contour detectable to a lesser degree.

scholarly journals Behavioural relevance of polarization sensitivity as a target detection mechanism in cephalopods and fishes

2011 ◽  
Vol 366 (1565) ◽  
pp. 734-741 ◽  
Author(s):  
Vincenzo Pignatelli ◽  
Shelby E. Temple ◽  
Tsyr-Huei Chiou ◽  
Nicholas W. Roberts ◽  
Shaun P. Collin ◽  
...  
Keyword(s):  
Target Detection ◽  
Polarized Light ◽  
Luminance Contrast ◽  
Polarization Sensitivity ◽  
Prey Detection ◽  
Free Swimming ◽  
Detection Mechanism ◽  
Set Up ◽  
Polarization Of Light

Aquatic habitats are rich in polarized patterns that could provide valuable information about the environment to an animal with a visual system sensitive to polarization of light. Both cephalopods and fishes have been shown to behaviourally respond to polarized light cues, suggesting that polarization sensitivity (PS) may play a role in improving target detection and/or navigation/orientation. However, while there is general agreement concerning the presence of PS in cephalopods and some fish species, its functional significance remains uncertain. Testing the role of PS in predator or prey detection seems an excellent paradigm with which to study the contribution of PS to the sensory assets of both groups, because such behaviours are critical to survival. We developed a novel experimental set-up to deliver computer-generated, controllable, polarized stimuli to free-swimming cephalopods and fishes with which we tested the behavioural relevance of PS using stimuli that evoke innate responses (such as an escape response from a looming stimulus and a pursuing behaviour of a small prey-like stimulus). We report consistent responses of cephalopods to looming stimuli presented in polarization and luminance contrast; however, none of the fishes tested responded to either the looming or the prey-like stimuli when presented in polarization contrast.

Central-Cue Discriminability Modulates Object-Based Attention by Influencing Spatial Attention

2012 ◽  
Vol 59 (3) ◽  
pp. 132-137 ◽  
Author(s):  
Morris Goldsmith ◽  
Menahem Yeari
Keyword(s):  
Spatial Attention ◽  
Luminance Contrast ◽  
Attentional Focus ◽  
Perceptual Representation ◽  
Object Representations ◽  
Attentional Deployment ◽  
Object Based ◽  
Target Locations ◽  
Central Arrow

The role of central-cue discriminability in modulating object-based effects was examined using Egly, Driver, and Rafal’s (1994) “double-rectangle” spatial cueing paradigm. Based on the attentional focusing hypothesis (Goldsmith & Yeari, 2003), we hypothesized that highly discriminable central-arrow cues would be processed with attention spread across the two rectangles (potential target locations), thereby strengthening the perceptual representation of these objects so that they influence the subsequent endogenous deployment of attention, yielding object-based effects. By contrast, less discriminable central-arrow cues should induce a more narrow attentional focus to the center of the display, thereby weakening the rectangle object representations so that they no longer influence the subsequent attentional deployment. Central-arrow-cue discriminability was manipulated by size and luminance contrast. The results supported the predictions, reinforcing the attentional focusing hypothesis and highlighting the need to consider central-cue discriminability when designing experiments and in comparing experimental results.

scholarly journals Color tuning of neurons in face patches of macaque inferior temporal cortex

2019 ◽  
Author(s):  
Marianne Duyck ◽  
Tessa J. Gruen ◽  
Lawrence Y. Tello ◽  
Serena Eastman ◽  
Joshua Fuller-Deets ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Temporal Cortex ◽  
Luminance Contrast ◽  
Macaque Monkey ◽  
Inferior Temporal Cortex ◽  
Color Tuning ◽  
Quantitative Measurements ◽  
Cone Activity ◽  
Insight Into

Previous work has shown that under viewing conditions that break retinal mechanisms for color, one class of objects appears paradoxically colored: faces, and they look green. Interpreted within a Bayesian-observer framework, this observation makes the surprising prediction that face-selective neurons are sensitive to color and weakly biased for colors that elicit L>M cone activity (warm colors). We tested this hypothesis by measuring color-tuning responses of face-selective cells in alert macaque monkey, using fMRI-guided microelectrode recording of the middle and anterior face patches and carefully color-calibrated stimuli. The population of face-selective neurons showed significant color tuning when assessed using images that preserved the luminance contrast relationships of the original face photographs. A Fourier analysis of the color-tuning responses uncovered two components. The first harmonic was biased towards the L>M colors, consistent with the prediction. Interestingly, the second harmonic aligned with the S-cone cardinal axis, which may relate to the computation of animacy by IT cells.SignificanceThe results provide the first quantitative measurements of the color tuning properties of face-selective neurons. The results provide insight into the neural mechanisms that could support the role of color in face perception.

A Theory of Illusory Lightness and Transparency in Monocular and Binocular Images: The Role of Contour Junctions

Perception ◽  
1997 ◽  
Vol 26 (4) ◽  
pp. 419-453 ◽  
Author(s):  
Barton L Anderson
Keyword(s):  
Illumination Change ◽  
Discontinuous Change ◽  
Illusory Contours ◽  
Contrast Polarity ◽  
Color Spreading ◽  
Transparent Surface ◽  
Neon Color Spreading ◽  
Lower Contrast

A theory of illusory transparency and lightness is described for monocular and binocular images containing X-, T- and I-contour junctions. This theory asserts that the geometric and luminance relationships of contour junctions induce illusory transparency and lightness percepts by causing a phenomenal scission of a homogenous luminance into multiple contributions. Specifically, it is argued that a discontinuous change in contrast along aligned contours that preserve contrast polarity induces a scission of the lower contrast region into a near-transparent surface or an illumination change, and a more distant surface that continues behind this near layer. This scission is assumed to cause changes in perceived lightness and/or surface opacity. Discontinuous changes in contrast along contours also are assumed to induce end-cut illusory contours that run roughly perpendicular to the inducing orientation of the contour, both monocularly and binocularly. Binocular illusory contours are shown to be caused by the presence of unmatchable contour terminators. It is argued that the presented theory can provide a unified account of a variety of monocular and binocular illusions that induce uniform transformations in perceived lightness, including neon-color spreading, the Munker – White illusion, Benary's illusion, and illusory monocular and binocular transparency.

scholarly journals Rapid scene categorization: Role of spatial frequency order, accumulation mode and luminance contrast

2015 ◽  
Vol 107 ◽  
pp. 49-57 ◽  
Author(s):  
Louise Kauffmann ◽  
Alan Chauvin ◽  
Nathalie Guyader ◽  
Carole Peyrin
Keyword(s):  
Spatial Frequency ◽  
Luminance Contrast ◽  
Scene Categorization ◽  
Accumulation Mode
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