Background

Gustav Fechner (1801–1887) is generally considered the founder of psychophysics, the study of the relation between physical stimuli and perception. Fechner’s book, Elements of Psychophysics, is often considered the beginning of the psychological study of sensation and perception (Fechner, 1860/1966). Fechner discovered the illusion known as the Fechner color effect, by which moving black-and-white figures create an illusion of color.

The most typical way to create these illusory color effects, often called Fechner colors, is to use a spinning pattern. It was actually first first a top, created by toymaker Charles Behnam in 1895 (von Campenhausen & Schramme, 1995). In this illustration, even though it is on a computer, we will use this same pattern to create Fechner Colors.

von Campenhausen, C. & Schramme, J. (1995). 100 years of Benham's top in colour science. Perception, 24(6), 695–717.

Instructions

Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab

Settings

Below is a list of the ways that you can alter the illustration. The settings include the following:

Spin/Stop: starts or stops Benham's top from spinning. The text of the button changes to reflect the current action it will perform.
Change Direction: causes the top to spin in the opposite direction.
Speed (deg/update): changes the speed of rotation of the top. The default usually does a good job of generating Fechner Colors, but it might change the speed so you can see if that changes your experience.

Reset

Pressing this button restores the settings to their default values.