Ishihara Color Test, 24 Plate Edition, by Shinobu Ishihara, M.D., Dr. Med. Sc., Professor Emeritus of the University of Tokyo, and member of the Japan Academy. Dr. Ishihara's color perception tests are recognized internationally as a highly reliable method of determining red/green color deficiency.
Ishihara's color plates are designed to be appreciated correctly in a room which is lit adequately by daylight. The introduction of direct sunlight or the use of elecric light may produce some discrepency in the results because of an alteration in the appearance of shadows of color. When it is convenient only to use electric light, it should be adjusted as far as possible to resemble the effect of natural daylight. The plates are held 75cm from the subject and tilted so that the plane of the paper is at right angle to the line of vision. The correct position of each color plate is indicated by the number which is printed on the back of the plate. The numerals which are seen on plates 1-17 are stated, and each answer should be given without more than 3 seconds delay. If the subject is unable to read numerals, plates 18-24 are used and the winding lines between the two x's are traced with a brush. Each tracing should be completed within 10 seconds. It is not necessary in all cases to use the whole series of plates. Plates 16 and 17 may be omitted if the test is designed merely to separate those with normal color appreciation form those with defective color appreciation. In a large scale examination, the test may be simplified to an examination of six plates only; No. 1, one of numbers 2, 3, one of numbers 4, 5, 6, 7, one of numbers 8, 9, one of numbers 10, 11, 12, 13, and one of numbers 14, 15.
The Ishihara Color Test is also available in 14
, and 38 Plate