Difference between revisions of "White's illusion" - New World Encyclopedia

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[[Image:White_illusion.png|frame|225px|White's illusion]]
 
  
'''White's illusion''' is an [[optical illusion]] illustrating the fact that the same target [[luminance]] can elicit different perceptions of [[brightness]] in different contexts.
 
  
Note, that although the gray rectangles are all of equal [[luminance]], the ones seen in the context with the dark stripes appear brighter than the ones seen in the context with the bright stripes. Note that this effect is opposite to what would be expected from a simple physiological explanation on the basis of [[simultaneous contrast]] (in that case the rectangles sharing the long borders with the dark stripes should appear brighter).
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'''White's illusion''' is an [[optical illusion]] illustrating the fact that the same target [[luminance]] can elicit different perceptions of [[brightness]] in different contexts. White's illusion is sometimes combined with the Munker illusion (a similar illusion that uses colors instead of grayscale) and referred to as the "Munker-White" illusion.
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==Discovery==
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White's illusion was discovered in 1979 by White, who published his findings in an issue of the psychological journal ''Perception''.  
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[[Image:White_illusion.png|frame|225px|White's illusion]]
  
[[Television]] screens depend on this visual illusion. [[Pixel]]s that are not illuminated are seen as black, when they are really the same dim gray seen when the television is turned off. An even more extreme example is an [[overhead projector]] screen, which is bright white in reality but whose less-illuminated regions appear black. Note that this is an effect of [[simultaneous contrast]], not White's illusion, per se.
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==Description==
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White's illusion is made up of a series of black and white horizontal bars. On one side, shorter gray bars cover the black bars; on the other side, they cover the white bars. When observing the image, it appears as though the gray bars surrounded by white stripes are definitively lighter than the gray bars surrounded by black stripes. In addition to appearing lighter, the gray bars surrounded by white also appear to be brighter, or of higher [[luminance]].
  
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==Explanation==
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The effect of the White illusion is opposite to what would be expected from a simple physiological explanation on the basis of [[simultaneous contrast]] (the rectangles sharing the long borders with the dark stripes should appear brighter, not darker). While the effect is not fully understood, theories have been advanced to explain the mechanism that causes the White illusion.
  
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Some theories stay within the framework of simultaneous contrast, but propose that the reactions of different parts of the visual system are responsible for the illusion. Other theories propose that the processing of the T-junctions (the area where the gray stripes intersect adjacent stripes) create the illusion.<ref>Anderson, Barton L. [http://www2.psy.unsw.edu.au/Users/BAnderson/TexturedWhites.pdf "Perceptual organization and White's illusion"] ''Perception, 2003. Vol 32. pp. 269-284. Retrieved October 30, 2007.</ref>
  
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==Applications==
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The fact that White's illusion behaves in opposition to what would be expected by physiological mechanisms such as simultaneous contrast and [[lateral inhibition]] has sparked scientists and researchers into an attempt to discover the actual mechanism that causes the effect. The fact that this illusion contradicts previous assumptions about the visual system may help scientists to come to a better understanding of the mechanisms involved in vision and perception.
  
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==Notes==
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<references/>
  
{{Credits|White's_illusion|83147402}}
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==References==
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*Ninio, Jacques. ''The Science of Illusions'' April 2001. Cornell University Press. ISBN 0801437709
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*Seckel, Al. ''The Art of Optical Illusions'' September 2000. Carlton Books. ISBN 1842220543

Revision as of 14:09, 30 October 2007


White's illusion is an optical illusion illustrating the fact that the same target luminance can elicit different perceptions of brightness in different contexts. White's illusion is sometimes combined with the Munker illusion (a similar illusion that uses colors instead of grayscale) and referred to as the "Munker-White" illusion.

Discovery

White's illusion was discovered in 1979 by White, who published his findings in an issue of the psychological journal Perception.

File:White illusion.png
White's illusion

Description

White's illusion is made up of a series of black and white horizontal bars. On one side, shorter gray bars cover the black bars; on the other side, they cover the white bars. When observing the image, it appears as though the gray bars surrounded by white stripes are definitively lighter than the gray bars surrounded by black stripes. In addition to appearing lighter, the gray bars surrounded by white also appear to be brighter, or of higher luminance.

Explanation

The effect of the White illusion is opposite to what would be expected from a simple physiological explanation on the basis of simultaneous contrast (the rectangles sharing the long borders with the dark stripes should appear brighter, not darker). While the effect is not fully understood, theories have been advanced to explain the mechanism that causes the White illusion.

Some theories stay within the framework of simultaneous contrast, but propose that the reactions of different parts of the visual system are responsible for the illusion. Other theories propose that the processing of the T-junctions (the area where the gray stripes intersect adjacent stripes) create the illusion.[1]

Applications

The fact that White's illusion behaves in opposition to what would be expected by physiological mechanisms such as simultaneous contrast and lateral inhibition has sparked scientists and researchers into an attempt to discover the actual mechanism that causes the effect. The fact that this illusion contradicts previous assumptions about the visual system may help scientists to come to a better understanding of the mechanisms involved in vision and perception.

Notes

  1. Anderson, Barton L. "Perceptual organization and White's illusion" Perception, 2003. Vol 32. pp. 269-284. Retrieved October 30, 2007.

References
ISBN links support NWE through referral fees

  • Ninio, Jacques. The Science of Illusions April 2001. Cornell University Press. ISBN 0801437709
  • Seckel, Al. The Art of Optical Illusions September 2000. Carlton Books. ISBN 1842220543