Editing Optical illusion (section)

=== Perceptual organization ===
[[File:Two silhouette profile or a white vase.svg|thumb|Reversible figures and vase, or the [[Figure-ground (perception)|figure-ground]] illusion]]
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[[File:Duck-Rabbit illusion.jpg|thumb|[[Rabbit–duck illusion]]]]

To make sense of the world it is necessary to organize incoming sensations into information which is meaningful. [[Gestalt psychology|Gestalt psychologists]] believe one way this is done is by perceiving individual sensory stimuli as a meaningful whole.<ref name="Myers" /> Gestalt organization can be used to explain many illusions including the [[rabbit–duck illusion]] where the image as a whole switches back and forth from being a duck then being a rabbit and why in the [[Figure-ground (perception)|figure–ground]] illusion the figure and ground are reversible.{{cn|date=January 2025}}

[[File:Kanizsa triangle.svg|thumb|alt=In this there is no "Drawn" White Triangle. Click caption for an explanation.|[[Kanizsa's Triangle|Kanizsa's triangle]]]]
In addition, gestalt theory can be used to explain the [[Illusory Contours|illusory contours]] in the [[Kanizsa's Triangle|Kanizsa's triangle]]. A floating white triangle, which does not exist, is seen. The brain has a need to see familiar simple objects and has a tendency to create a "whole" image from individual elements.<ref name="Myers">Myers, D. (2003). Psychology in Modules, (7th ed.) New York: Worth. {{ISBN|0-7167-5850-4}}</ref> ''Gestalt'' means "form" or "shape" in German. However, another explanation of the Kanizsa's triangle is based in [[evolutionary psychology]] and the fact that in order to survive it was important to see form and edges. The use of perceptual organization to create meaning out of stimuli is the principle behind other well-known illusions including [[impossible objects]]. The brain makes sense of shapes and symbols putting them together like a jigsaw puzzle, formulating that which is not there to that which is believable.{{cn|date=January 2025}}

The [[Gestalt psychology#Theoretical framework and methodology|gestalt principles]] of perception govern the way different objects are grouped. Good form is where the perceptual system tries to fill in the blanks in order to see simple objects rather than complex objects. Continuity is where the perceptual system tries to disambiguate which segments fit together into continuous lines. Proximity is where objects that are close together are associated. Similarity is where objects that are similar are seen as associated. Some of these elements have been successfully incorporated into quantitative models involving optimal estimation or Bayesian inference.<ref>Yoon Mo Jung and Jackie (Jianhong) Shen (2008), J. Visual Comm. Image Representation, '''19'''(1):42–55, [http://portal.acm.org/citation.cfm?id=1326364.1326487&coll=&dl=&CFID=11849883&CFTOKEN=72040242 ''First-order modeling and stability analysis of illusory contours''].</ref><ref>Yoon Mo Jung and Jackie (Jianhong) Shen (2014), arXiv:1406.1265, [https://arxiv.org/abs/1406.1265 ''Illusory shapes via phase transition''] {{webarchive|url=https://web.archive.org/web/20171124185300/https://arxiv.org/abs/1406.1265 |date=2017-11-24 }}.</ref>

The double-anchoring theory, a popular but recent theory of lightness illusions, states that any region belongs to one or more frameworks, created by gestalt grouping principles, and within each frame is independently anchored to both the highest luminance and the surround luminance. A spot's lightness is determined by the average of the values computed in each framework.<ref>{{cite journal | last1 = Bressan | first1 = P | year = 2006 | title = The Place of White in a World of Grays: A Double-Anchoring Theory of Lightness Perception | url = http://osf.io/fht3g/| journal = Psychological Review | volume = 113 | issue = 3| pages = 526–553 | doi=10.1037/0033-295x.113.3.526 | pmid=16802880| hdl = 11577/1560501 | hdl-access = free }}</ref>