![Checkershadow double med](https://upload.wikimedia.org/wikipedia/commons/a/aa/Checkershadow_double_med.jpg)
The checker shadow illusion is an
optical illusion
Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide v ...
published by
Edward H. Adelson, professor of
vision science
Vision science is the scientific study of visual perception. Researchers in vision science can be called vision scientists, especially if their research spans some of the science's many disciplines.
Vision science encompasses all studies of vision ...
at
MIT
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
in
1995
File:1995 Events Collage V2.png, From left, clockwise: O.J. Simpson is O. J. Simpson murder case, acquitted of the murders of Nicole Brown Simpson and Ronald Goldman from the 1994, year prior in "The Trial of the Century" in the United States; The ...
.
Description
The image depicts a
checkerboard
A checkerboard (American English) or chequerboard (British English; see spelling differences) is a board of checkered pattern on which checkers (also known as English draughts) is played. Most commonly, it consists of 64 squares (8×8) of altern ...
with light and dark squares, partly shadowed by another object. The optical illusion is that the area labeled A appears to be a darker
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
than the area labeled B. However, within the context of the two-dimensional image, they are of identical brightness, ''i.e.'', they would be printed with identical mixtures of ink, or displayed on a screen with pixels of identical color.
Related illusions
Whilst being one of the most well-known
contrast illusions, there are similar effects which cause two regions of identical color to appear differently depending on context:
* The
Cornsweet illusion
The Cornsweet illusion, also known as the Craik–O'Brien–Cornsweet illusion or the Craik–Cornsweet illusion, is an optical illusion that was described in detail by Tom Cornsweet in the late 1960s. Kenneth Craik and Vivian O'Brien had mad ...
creates a boundary between two identically-shaded regions with a discontinuous gradient, resulting in the opposing sides appearing to be different.
* The
Chubb illusion
The Chubb illusion is an optical illusion or error in visual perception in which the apparent contrast of an object varies substantially to most viewers depending on its relative contrast to the field on which it is displayed. These visual illusi ...
evokes this effect by surrounding zones with others of different, distinct shades, with the relative brightness or darkness of the surrounded area appearing different.
* An illusion closely related to the checker shadow illusion, which also relies on using implied visual shadows to seemingly darken a brighter region to the same color as a well-lit dark region, involves two squares placed at an angle, with the darker square being lit and the lighter square at an angle which receives poor light.
See also
*
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, m ...
*
Color constancy
Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple f ...
*
The dress
The dress was a viral phenomenon on the Internet in 2015. Viewers of the image disagreed on whether the dress depicted in a photograph was coloured black and blue, or white and gold. The phenomenon revealed differences in human colour percept ...
References
External links
A high resolution remake of the illusionReal-life ProofExplanation of the effect– search for ‘simultaneous brightness contrast’
An interactive presentation of the effectAn interactive click-and-drag demonstration of the effect
{{Optical illusions
Optical illusions