Benham's Top

These animated demonstrations require Java Plug-in which is installed on most computers. You can easily find out if Java is working on your system.

Benham's top is one of many classic examples of subjective colors.   If you spin the black and white circular disk, you should be able to see faint colors in the position of the arcs. You can change the saturation of the perceived colors by adjusting the spinning speed with the scroll bar. Different sections of the arcs produce different colors from red to blue. Reversing the spinning will reverse the order of colors.

The following version was adapted in response to Josef K Nagler's suggestions

Sequential color change based on Josef K Nagler's 1956 US Patent (METHOD AND APPARATUS FOR PRODUCING COLOR):

The above panel has six identical groups each of which has three bars (hence 18 bars) - left, middle and right - corresponding to the inner, middle and outer sections of the arcs of the above disk. You can cover any groups or bars, the remaining subjective colors persist. You can use the speed control scroll bar to slow down the frame rate to see the image sequences that produce the subjective colors. You can also use the scroll bar to reverse the sequence and watch the subjective color pattern reverses accordingly.

(Originally Developed in November 1999)