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 oc ...

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 assoc ...

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. Benham's disc (animated)

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 ins ...

and

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

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 system ...

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 (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

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 and ...

, 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 th ...

accounts for all the different PIFCs. Benham's top and other PIFCs are being researched for use as a diagnostic tool for diseases of the eye and the visual track. It has shown particular promise in detecting

optic neuritis Optic neuritis describes any condition that causes inflammation of the optic nerve; it may be associated with demyelinating diseases, or infectious or inflammatory processes. It is also known as optic papillitis (when the head of the optic nerv ...

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 A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...

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
{{DEFAULTSORT:Fechner Color Optical illusions Color

Benham's top

See also

References

External links