The Fechner color effect is an

illusion An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people. Illusions may ...

color Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though co ...

seen when looking at certain rapidly changing or moving black-and-white patterns. They are also called pattern induced flicker colors (PIFCs). The effect is most commonly demonstrated with a device known as Benham's top (also called Benham's disk). When the top is spun, arcs of pale color are visible at different places on the disk that forms its upper surface. The effect can also be seen in stroboscopic lights when flashes are set at certain critical speeds. Rotating fan blades, particularly aluminum ones, can also demonstrate the effect; as the fan accelerates or decelerates, the colors appear, drift, change and disappear. The stable running speed of the fan does not (normally) produce colors, suggesting that it is not an interference effect with the frequency of the illumination flicker. The effect was noted by

Gustav Fechner Gustav Theodor Fechner (; ; 19 April 1801 – 18 November 1887) was a German physicist, philosopher, and experimental psychologist. A pioneer in experimental psychology and founder of psychophysics (techniques for measuring the mind), he inspi ...

and

Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz (; ; 31 August 1821 – 8 September 1894; "von" since 1883) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The ...

and propagated to English-speakers through Charles Benham's invention of his top. Florence Winger Bagley was one of the early investigators of this phenomenon. The

perceptual Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous syste ...

mechanism of Fechner color is not entirely understood. One possible reason people see colors may be that the color receptors in the human eye respond at different rates to red, green, and blue. Or, more specifically, that the latencies of the center and the surrounding mechanisms differ for the different types of color-specific ganglion cells. The phenomenon originates from neural activity in the

retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

and spatial interactions in the

primary visual cortex The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus ...

, which plays a role in encoding low-level image features, such as edges and spatiotemporal frequency components. Research indicates that the blue–yellow

opponent process The opponent process is a color theory that states that the human visual system interprets information about color by processing signals from photoreceptor cells in an antagonistic manner. The opponent-process theory suggests that there are thre ...

accounts for all the different PIFCs. Research has been done into the use of Benham's top and other PIFCs as diagnostic tools for diseases of the eye and the visual track. It has shown particular promise in detecting

optic neuritis Optic neuritis (ON) is a debilitating condition that is defined as inflammation of cranial nerve II which results in disruption of the neurologic pathways that allow visual sensory information received by the retina to be able to be transmitted to ...

Benham's top

Benham's top is named after the English newspaper-man, amateur scientist, and toymaker Charles Benham, who in 1895 sold a

top Top most commonly refers to: * Top, a basic term of orientation, distinguished from bottom, front, back, and sides * Spinning top, a ubiquitous traditional toy * Top (clothing), clothing designed to be worn over the torso * Mountain top, a moun ...

painted with the pattern shown. Benham was inspired to propagate the Fechner color effect through his top after his correspondence with

Gustav Theodor Fechner Gustav Theodor Fechner (; ; 19 April 1801 – 18 November 1887) was a German physicist, philosopher, and experimental psychologist. A pioneer in experimental psychology and founder of psychophysics (techniques for measuring the mind), he inspired ...

, who had observed and demonstrated the said effect. Benham's top made it possible for speakers of the English language to learn of the Fechner color effect, about which Fechner's original reports were written in German.

References

External links

Online Java demonstrations of Fechner color

() by Michael Bach
A more convincing interactive version from Michael Bach

Why Do Colors Appear in Benham’s Top?
by Yutaka Nishiyama {{DEFAULTSORT:Fechner Color Optical illusions Color

Benham's top

See also

References

External links