Benham's top
Encyclopedia
Charles Benham
Charles Edwin Benham JP was a journalist, editing for many years the Essex County Standard, a published author of works such as Essex Ballads and an amateur scientist-cum-inventor, which led him to create Benham's top, which was named after him....
, who, in 1895, sold a top painted with the pattern shown. When the disk is spun, arcs of pale color — called Fechner colors or pattern induced flicker colors (PIFCs) — are visible at different places on the disk. Not everyone sees the same colors.
The phenomenon 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. More specifically, 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
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
and spatial interactions in the primary visual cortex, which processes pattern recognition. Research indicates that the blue-yellow opponent process
Opponent process
The color opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner...
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
Optic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
.