Anchoring of Surface Lightness by Area and Luminance

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 153-153
Author(s):  
A L Gilchrist
Keyword(s):  
Relative Area ◽  
Stimulus Contrast ◽  
Lightness Perception ◽  
Empirical Results ◽  
Average Luminance ◽  
The Many ◽  
Surface Lightness ◽  
Luminance Range

Relative luminance is fundamental to lightness perception, but can be used to predict specific lightness values only when coupled with an anchoring rule. Empirical results indicate that, in simple displays, lightness is anchored by the highest luminance (white) rather than by the average luminance (middle gray). This implies that increasing the luminance range of a stimulus causes grayness induction: the lower luminance values become darker gray while the highest luminance remains unchanged, as many so-called brightness induction experiments have shown. Yet sometimes increasing the luminance range of a stimulus causes luminosity induction: the highest luminance becomes increasingly self-luminous while the lowest luminances remain unchanged. Whether grayness induction or luminosity induction results from an increase in stimulus contrast depends on relative area. A few simple, yet hitherto unrecognised, rules that describe how anchoring by highest luminance combines with anchoring by largest area appear to be consistent with the many published reports on area and lightness/brightness. These findings add to the accumulating evidence that many phenomena previously attributed to contrast are much better understood in terms of anchoring.

Lightness Perception Can Be Affected by Surface Curvature from Stereopsis

Perception ◽  
1994 ◽  
Vol 23 (8) ◽  
pp. 869-881 ◽  
Author(s):  
David Buckley ◽  
John P Frisby ◽  
Jonathan Freeman
Keyword(s):  
Present Report ◽  
Three Dimensional ◽  
Surface Shape ◽  
Sharp Change ◽  
Planar Surface ◽  
Lightness Perception ◽  
Starting Point ◽  
Integrated Interpretation ◽  
Shape Data ◽  
Surface Lightness

It is demonstrated that lightness perception can be affected by shape from stereopsis. The starting point was a report by Knill and Kersten that the perceived lightness of a monocularly viewed surface can be affected by outline-contour cues indicating that the surface is three-dimensional (3-D). In that study stimuli consisted of two equally sized abutting regions each having the same vertical linear-intensity ramp, so that the horizontal abutting boundary of the two patches created a sharp change in intensity. When this version of the Craik-O'Brien - Cornsweet stimulus has a rectangular outline, it exhibits the standard simultaneous contrast illusion: equivalent patches in the top and bottom regions appear to have different brightness despite having the same luminance. Knill and Kersten replicated this phenomenon with stimuli whose outline-contour cues were consistent with a flat (planar) surface. They found, however, that the illusion was greatly reduced in stimuli with outlines consistent with two abutting 3-D quarter cylinders, for which equivalent regions in the two halves appeared of similar lightness. Knill and Kersten interpreted this effect in terms of surface-lightness computations that took into account 3-D surface shape to achieve an integrated interpretation of the luminance and shape data. In the present report three experiments are described for which these earlier findings were taken as the starting point. In the first experiment the results were replicated by the use of a different methodology. In the second experiment it was shown that shape-from-stereo can produce similar effects on lightness perception to that caused by shape-from-contour. Real 3-D objects with curved surfaces, luminance profiles of the Knill and Kersten type, and carefully controlled outline-contour cues were used so that the objects appeared flat when viewed monocularly but curved in 3-D when seen binocularly. The third experiment was a control confirming that the stereo effect was not simply due to differences caused by monocular versus binocular viewing. It is concluded that the human visual system uses stereo cues, as well as outline-contour cues, in the interpretation of luminance data to recover surface lightness.

scholarly journals The effects of global grouping laws on surface lightness perception

2004 ◽  
Vol 66 (5) ◽  
pp. 792-799 ◽  
Author(s):  
Songjoo Oh ◽  
Jung-Oh Kim
Keyword(s):  
Lightness Perception ◽  
Surface Lightness

scholarly journals Relative area and relative luminance combine to anchor surface lightness values

1999 ◽  
Vol 61 (5) ◽  
pp. 771-785 ◽  
Author(s):  
Xiaojun Li ◽  
Alan L. Gilchrist
Keyword(s):  
Relative Area ◽  
Surface Lightness

scholarly journals Local and global processes in surface lightness perception

1995 ◽  
Vol 57 (2) ◽  
pp. 125-135 ◽  
Author(s):  
Joseph Cataliotti ◽  
Alan Gilchrist
Keyword(s):  
Lightness Perception ◽  
Surface Lightness

scholarly journals The role of serendipity in drug discovery

2006 ◽  
Vol 8 (3) ◽  
pp. 335-344 ◽  
Keyword(s):  
Drug Discovery ◽  
Psychotropic Drugs ◽  
Pharmacological Treatment ◽  
Chloral Hydrate ◽  
Potassium Bromide ◽  
Lysergic Acid ◽  
Lysergic Acid Diethylamide ◽  
Empirical Results ◽  
The Many

Serendipity is one of the many factors that may contribute to drug discovery. It has played a role in the discovery of prototype psychotropic drugs that led to modern pharmacological treatment in psychiatry. It has also played a role in the discovery of several drugs that have had an impact on the development of psychiatry. "Serendipity" in drug discovery implies the finding of one thing while looking for something else. This was the case in six of the twelve serendipitous discoveries reviewed in this paper, i.e., aniline purple, penicillin, lysergic acid diethylamide, meprobamate, chlorpromazine, and imipramine. In the case of three drugs, i.e., potassium bromide, chloral hydrate, and lithium, the discovery was serendipitous because an utterly false rationale led to correct empirical results; and in case of two others, i.e., iproniazid and sildenafil, because valuable indications were found for these drugs which were not initially those sought The discovery of one of the twelve drugs, chlordiazepoxide, was sheer luck.

Identifying suboptimalities with factorial model comparison

2018 ◽  
Vol 41 ◽  
Author(s):  
Wei Ji Ma
Keyword(s):  
Experimental Design ◽  
Model Comparison ◽  
Process Models ◽  
Multiple Forms ◽  
Factorial Experimental Design ◽  
Factorial Model ◽  
Multiple Components ◽  
The Many

AbstractGiven the many types of suboptimality in perception, I ask how one should test for multiple forms of suboptimality at the same time – or, more generally, how one should compare process models that can differ in any or all of the multiple components. In analogy to factorial experimental design, I advocate for factorial model comparison.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

The many faces of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Tomasello
Keyword(s):  
Third Party ◽  
The Many ◽  
Sense Of Obligation

Abstract My response to the commentaries focuses on four issues: (1) the diversity both within and between cultures of the many different faces of obligation; (2) the possible evolutionary roots of the sense of obligation, including possible sources that I did not consider; (3) the possible ontogenetic roots of the sense of obligation, including especially children's understanding of groups from a third-party perspective (rather than through participation, as in my account); and (4) the relation between philosophical accounts of normative phenomena in general – which are pitched as not totally empirical – and empirical accounts such as my own. I have tried to distinguish comments that argue for extensions of the theory from those that represent genuine disagreement.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

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