Today we look at Tests for Colour Blindness by Shinobu Ishihara.
The Ishihara Colour Test is a test for red-green color deficiencies. It was named after its designer, Dr. Shinobu Ishihara, a professor at the University of Tokyo, who first published his tests in 1917. The test consists of a number of colored plates, called Ishihara plates, each of which contain a circle of dots, randomised in color and size. Within the pattern are dots which form a number visible to those with normal color vision and invisible, but difficult to see for those with a red-green colour vision defect. The full test consists of 38 plates. Common plates include a circle of dots in shades of green and light blues with a figure differentiated in shades of brown, or a circle of dots in shades of red, orange and yellow with a figure in shades of green.