Ishihara test

English

Ishihara test plate showing the number 74. People with red-green color blindness may see the number 21. People with monochromatic vision may not see a number at all.

Etymology

Devised by Shinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917.

Noun

Ishihara test (plural Ishihara tests)

1. A test for red-green color blindness, using a number of colored plates (Ishihara plates), each of which contains a circle of dots of various colors and sizes. Depending on the person's vision, certain dots within the pattern will appear to form recognizable numbers or shapes.
   • 1935 May, Mary S. Millard, David Shakow, “A NOTE ON COLOR-BLINDNESS IN SOME PSYCHOTIC GROUPS”, in The Journal of Social Psychology, volume 6, number 2, →DOI, →ISSN, page 252:

     In order to check on a clinically derived impression of a greater incidence of color-blindness among psychotic patients, the Ishihara Test (5) was given to a group of patients at the Worcester State Hospital.