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Topic: Cafe wall illusion

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	Café wall illusion - Wikipedia, the free encyclopedia
		He observed this curious effect in the tiles of the wall of a café at the bottom of St Michael's Hill, Bristol.
		To construct the illusion, alternating light and dark "bricks" are laid in staggered rows.
		It is essential for the illusion that each "brick" is surrounded by a layer of "mortar" (the grey in the image).
	en.wikipedia.org /wiki/Cafe_wall_illusion (156 words)

	Professor Richard Gregory on-line
		The Cafe Wall illusion (seen on the tiles of a local café) is a Münsterberg chequerboard figure, but with horizontal parallel lines which may have any luminance separating the rows of displaced squares.
		The Café Wall illusion is attributed to this border locking producing inappropriate contour shifts from neighbouring regions of contrasting luminance when separated by narrow gaps of neutral luminance.
		It is to this we attribute the Café Wall illusion.
	richardgregory.org /papers/cafe_wall/cafe-wall_p1.htm (1822 words)

	Optical illusion - the free encyclopedia (Site not responding. Last check: 2007-09-29)
		Many are physiological illusions, such as the Cafe wall illusion which exploits the early visual system encoding for edges.
		Paradox illusions offer objects that are paradoxical or impossible, such as the Penrose triangle or impossible staircasesseen, for example, in the work of M.
		Fiction illusions are the perception of objects that are genuinely not there to all but a single observer, such as thoseinduced by schizophrenia or hallucinogenic drugs.
	www.free-web-encyclopedia.com /?t=Oi (526 words)

	Illusion
		Café wall illusion The café wall illusion is an Bristol.
		Illusion An illusion is a distortion of a sensory senses can be deceived by illusions, but visual illusions are the most...
		Illusion of control The illusion of control is the tendency for human beings to believe they can control or at least inf...
	www.brainyencyclopedia.com /topics/illusion.html (488 words)

	Studies in Visual Perception, III.
		The famous and much-studied Cafe Wall illusion, introduced in the paper "Border locking and the Cafe Wall illusion" by Richard L. Gregory and Priscilla Heard, Perception, 1979, v 8, pp 365-380,available on line at [get paper] seems never to have been fully understood.
		Superposition of the T-junctions of the ordinary Cafe Wall illusion on the checkerboard taken from the 'progressive' form of the illusion.
		Since the Cafe Wall illusion is intensity, not color, dependent, we can assign random colors to its bricks, as long as the resulting brick luminance does not bring the brick to the other side of the general mortar luminance.
	www.settheory.com /Glass_paper/cafe_wall_study.html (2048 words)

	Café Wall Illusion
		The Café Wall Illusion was first reported by Richard L. Gregory and Priscilla Heard in 1979.
		This illusion demonstrates the effect of some simple image processing occurring at the retina combined with some complex processing in the cortical cells of the striate cortex.
		Lulich DP and Stevens KA (1989) Differential contributions of circular and elongated spatial filters to the Café Wall illusion.
	www.michaelbach.de /ot/ang_cafewall (260 words)

	Visual and Auditory Illusions
		Illusions, by definition, are phenomena that we perceive in a way that differs from their actual nature.
		If we can recreate such an illusion on a computer, then we know that the computer display itself is capable of operating at the limits of our perceptual abilities, at least in the respects relevant to the particular illusion.
		Although illusions should not generally be considered a precise diagnostic tool, they can nevertheless be helpful in a coarse evaluation of a display environment.
	www.cs.ubc.ca /nest/imager/contributions/flinn/Illusions/Illusions.html (1017 words)

	Optical illusion -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-09-29)
		An optical illusion is any (Something many people believe that is false) illusion that deceives the human (The sensory system for vision) visual system into (additional info and facts about perceiving) perceiving something that is not present or incorrectly perceiving what is present.
		A (An optical illusion in which atmospheric refraction by a layer of hot air distorts or inverts reflections of distant objects) mirage is a natural illusion that is an (A physical phenomenon related to or involving light) optical phenomenon.
		Paradox illusions offer objects that are paradoxical or impossible, such as the (additional info and facts about Penrose triangle) Penrose triangle or (additional info and facts about impossible staircases) impossible staircases seen, for example, in the work of (additional info and facts about M. Escher) M.
	www.absoluteastronomy.com /encyclopedia/o/op/optical_illusion.htm (829 words)

	The Cafe Wall Illusion
		The Café Wall Illusion was first reported by Richard L. Gregory and Priscilla Heard in 1979 [Gregory-79].
		The mortar between adjacent rows of tiles was visually apparent, and the fl/white pattern was offset by half a tile width in alternating rows.
		Consider the portion of the demonstration in which the tiles are dark and light gray (rather than completely fl and white), and the mortar colour is changed slowly from fl to white.
	www.cs.ubc.ca /nest/imager/contributions/flinn/Illusions/CW/cw.html (1454 words)

	BrainConnection Print This Page (Site not responding. Last check: 2007-09-29)
		The cafe wall illusion is a study in how the visual system detects overall features of an image.
		When looking at the wall, one tends to see alternating layers that change in perspective with the lines of bricks appearing narrow on one side and wider on the other.
		Each mortar line in the café wall illusion is perceived as sloping down and right or down and left in an alternating sequence.
	brainconnection.com /teasers/printindex.php3?main=illusion/cafe-wall (604 words)

	Optical Illusions Etc: free, scary, word & picture illusions
		These Optical Illusions are presented on this blog in the spirit of providing an entertaining venue to educate those interested in optical illusions and expanding the traditional assumptions of what constitutes an optical illusion.
		Paradox illusions offer objects that are paradoxical or impossible, such as the Penrose triangle or impossible staircases seen, for example, in the work of M.
		Fiction illusions are the perception of objects that are genuinely not there to all but a single observer, such as those induced by schizophrenia or hallucinogenic drugs.
	illusionsetc.blogspot.com /2004/05/what-are-optical-illusions.html (840 words)

	The eyes don't always have it / Professor shows how visual cues can deceive
		A shadowed side of the Campanile, for instance, can be made to darken dramatically, but only if you are able to mentally "flip" the image of the 307- foot tower so that the corner closest to you becomes an inside edge of a concave form.
		From here, downtown Berkeley looked to be built on essentially level ground as the hills gave way to the bay, creating the illusion that the water in the bay was pitched higher than the top of the tallest downtown building.
		"Illusions are just very obvious examples of situations where our brain uses all the information it has to estimate a property of the world, but makes a mistake," said James Hillis, a postdoctoral fellow at the University of Pennsylvania and former graduate student in Banks' lab.
	www.sfgate.com /cgi-bin/article.cgi?f=/c/a/2002/12/02/MN219975.DTL (1027 words)

	[No title]
		The Caf Wall Illusion Even if we know that the lines of mortar are all straight, we see them as sloping.
		Illusions are cases where we find significant differences between perceived and measured reality (a very broad definition) Physical Illusions A straw in a glass of water may appear broken at the surface of the water, and its size and angle different under the water.
		These are examples of physical illusions, where what we see is not really there, but where the cause of the illusion in the behaviour of light before it reaches the eye.
	www.psychology.nottingham.ac.uk /staff/prc/c81hca/lect7.doc (692 words)

	ipedia.com: Optical illusion Article (Site not responding. Last check: 2007-09-29)
		Optical illusions can occur naturally or be demonstrated by specific visual tricks that show particular assumptions in the human perceptual system.
		A mirage is an example of a natural illusion that is an optical phenomenon.
		Physiological illusions, such as the afterimages following bright lights or adapting stimuli of prolonged alternating patterns (contingent perceptual aftereffect, CAE), are the effects on the eyes or brain of prolonged stimulation of a specific type - brightness, tilt, colour, movement, and so on.
	www.ipedia.com /optical_illusion.html (582 words)

	Practical skills Cognitive Psychology (Site not responding. Last check: 2007-09-29)
		Visual illusions are often present in nature and appear when you least expect it.
		Since the nineteenth century when scientists became interested in perception, illusions have been used as tools in the study of perception.
		Collection of illusions of brightness, illusions of subjective contours, illusions of color, illusions of motion, geometrical illusions, and other illusions
	www.cs.unimaas.nl /lacroix/KCP20042005/Stroop_and_VisualIllusions.htm (884 words)

	Illusion news
		The silhouette illusion or rotating lady's figure (reversible between clockwise and counterclockwise) is the most striking movie among reversible moving images that I have ever seen.
		The apparatus for the experiment of the rubber pencil illusion, in which the inner bar is swayed in a mechanical fashion.
		Kitaoka, A. and Ashida, H. (2003) Phenomenal characteristics of the peripheral drift illusion.
	www.psy.ritsumei.ac.jp /~akitaoka/illnewse.html (857 words)

	[No title] (Site not responding. Last check: 2007-09-29)
		When you look at the Café Wall, you should see the 'mortar lines' (the horizontal lines between the tiles) slope alternately upward and downward to the right.
		The Café Wall illusion demonstrates the effect of some simple image processing occurring at the retina combined with some complex processing in the cortical cells of the striate cortex.
		Lulich, D.P. and Stevens, K.A. Differential Contributions of Circular and Elongated Spatial Filters to the Café Wall Illusion.
	www.uvm.edu /~awager/Illusions/Cafe.html (204 words)

	More Activities: Cafe Wall Illusion
		Get the children to look at a number of different optical illusions before doing this task.
		The cafe wall illusion works best when you use fl and white rectangles.
		yellow and white, the illusion effect is smaller or can not be seen.
	www.msm.cam.ac.uk /seek/cafe_illusion.htm (360 words)

	Visual Illusions Gallery : Index
		Illusions in visual perception occur when experiences, which people report, do not correspond to physical measurements of stimuli.
		Humans would not have successfully adapted to survive and thrive in the environment of earth if there were not psychophysical correspondence between distal stimuli and most experiences.
		Illusions are instances which lack correspondence and these instances can be very informative in helping us to understand how we are structured, how we function, and how we can best represent the world around us.
	dragon.uml.edu /psych/illusion.html (386 words)

	Perception (Site not responding. Last check: 2007-09-29)
		This illusion of a floating disk even works with one eye closed, and the further away you are from the image, the deeper the central circle appears until it looks like a hole with a lens moving over a cut-out.
		Combinations of the Café Wall and Mach Bands illusions, which also produces a sense of each row moving in opposite directions.
		It is clear in the first image that the centre grey is constant, but as soon as the image is split, each part seems differrent.
	www.palmyra.demon.co.uk /illusion/perception/perception.htm (432 words)

	Surfing The Net With Kids
		Optical illusions are amusing, but they also teach us a lot about how our brain works in conjunction with our eyes to create vision.
		You'll find the Cafe Wall Illusion on other sites as well, but here you get to interact with it and watch the distortion come and go.
		In addition to dozens of interactive illusions, unique clicks include Do-It-Yourself Projects ("Six easy-to-do optical illusion projects in Adobe PDF format to tempt the curious.") and a typography section.
	www.spokane.net /kids/z-0122.asp (503 words)

	Optical Illusions - Introduction
		The café wall illusion consists of a fl and white checkerboard pattern with alternating rows shifted one half of a block and with thin gray mortar lines separating the rows.
		If we take a closer look at the pattern, we find that the horizontal gray lines create two different types of edges because of their proximity to the fl and white blocks.
		Based on the understanding of how the illusion works we should be able to counteract the effect by introducing new elements into the picture that balance out the illusion.
	www.cfar.umd.edu /~fer/optical/smoothing2.html (313 words)

	Akiyoshi's illusion pages
		Hereafter, I grant permission to upload to your webpage up to three (3) images if your webpage is to discuss the science of illusion or vision, is not a commercial site, and does not contain indecent, obscene, or illegal content.
		It is my pleasure to grant permission for the use of my illusion material for papers, articles, or books if they are for educational or research purposes.
		For instance, the Ponzo illusion, if the image is the upper-converging version, is difficult to see.
	www.ritsumei.ac.jp /kic/~akitaoka/index-e.html (1086 words)

	CRS4 Publications (Site not responding. Last check: 2007-09-29)
		New variations of the spiral illusion are demonstrated.
		They include spiral illusions of the Cafe Wall illusion and the Zollner illusion, as well as other new orientation illusions.
		Thus the spiral illusion is not limited to the Fraser illusion.We discuss the role that detectors of spirals in a higher visual area might play in the spiral illusion.
	www.crs4.it /Publications/cgi-bin/crs4-bib.cgi?opt_style=page&opt_selectid=Brelstaff:2002:NVSa&opt_selecttype=Article (182 words)

	fun (Site not responding. Last check: 2007-09-29)
		Cafe Wall Illusion A famous illusion named after the pattern of tiles on a Cafe Wall in Bristol.
		This illusion reveals something about the perception of faces.
		The Muller-Lyer illusion results from confusion about the length of a horizontal line.
	www.essex.ac.uk /psychology/psychology/fun/funStuff.html (138 words)

	Cool Optical Illusions - Free Optical Illusion Desktop Wallpaper
		This is similar to the famous cafe wall optical illusion, because it has been found on a cafe wall in europe.
		The person who put in the tiles on the wall in the cafe staggered the tiles a little bit to give the illusion you can see below.
		Some optical illusions were created uniquely for this site, others are assumed to be in the public domain.
	www.coolopticalillusions.com /bricksillusionwallpaper.htm (506 words)

	Sensation and Perception - BEEMNET Neuroscience Education 2001 (Site not responding. Last check: 2007-09-29)
		The illusions included in this exhibit are: The Cafe Wall, The Hermann Grid, Motion Ambiguity, Shape from Motion, Backwards Speech, and Anti-images.
		Cafe Wall Illusion - Interactive exhibit on the apparent distortion in the pattern of rectangular bricks.
		The illusion depends on the alignment of bricks and color of the mortar.
	www.beemnet.com /dana/sensory.html (2780 words)

	Optical Illusions - Info on Cafe wall
		This has the effect of producing lots of wedges, which your brain puts together and decides you are looking at non-parallel wavy lines.
		Richard Gregory and his group are world experts on visual illusions, and use them as a way to understand how our eye and brain process visual information.
		After several months of theories, discussion and the building of interactive models, they had understood how our visual systems create the café wall illusion.
	www.at-bristol.org.uk /Optical/cafewall_more.htm (184 words)

	Shape Optical Illusions - Planet Perplex
		The name of this illusion is no coincidence : this was first noticed on the fl and white tiles of a café wall in Bristol.
		An Analysis of the Cafe Wall Illusion More than you ever wanted to know about the Cafe wall illusion.
		Because of the background with circles, your vision can't determine that the square is made up of straight lines.
	www.planetperplex.com /en/shape_illusions.html (165 words)

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