![]() ![]() When supplemented by information from other color vision tests, the results provided by this instrument permit the accurate classification of all color deficiencies. The anomaloscope is the standard instrument for the diagnosis of color vision defects. Most recently, Lanthony (1974b, 1975b) has developed two arrangement tests (the Lanthony Desaturated Panel D-15 and the Lanthony New Color Test) for use in diagnosing acquired color vision defects.Īnomaloscopes are optical instruments in which the observer must manipulate stimulus control knobs to match two colored fields in color and brightness. The Inter-Society Color Council of America (ISCC) employed colored plastics in the ISCC Color Aptitude Test, which involves saturation discrimination. Modern variants of arrangement tests involving hue discrimination were devised by Farnsworth (1943) in the FM 100-hue and the Panel D-15 tests. In the matching test, prearranged series of discs of one color were presented to the observer who then had to select their match from a duplicate group of discs. In the grading test, 16 discs of one hue were presented in random order to the observer, who had to arrange them in a saturation series. Applicants had two tasks to perform: to grade and then to match a series of nitrocellulose lacquer discs that varied in saturation and hue. Pierce's solution was to develop a surface color test in which color ability could be measured by an observer's skill in arranging and matching color series. All previously devised color vision tests were designed to separate color-defective observers from normal observers but did not indicate the wide range of color ability and aptitude that exists among normal observers. This kind of test was developed by Pierce (1934) and was first used in the National Institute of Industrial Psychology in London. Variants of the lantern test are still used today for testing transport workers and members of the armed forces of many countries.Īrrangement tests require the observer to arrange a set of colored samples in sequence. The advantage of such a test when applied vocationally is that the task can be made to simulate the real-life situation quite closely. In the lantern test, which was introduced by Williams (1903), colored signal lights were to be named by the observer. The spectral colors used by Rayleigh were incorporated by Nagel (1899, 1900, 1907) in his anomaloscope. It is agreed that the anomaloscope is the only clinical method capable of classifying the color defects by their presumed genetic entities. Lord Rayleigh (1881), using his color mixing apparatus, which employed narrow spectral bands of red and green to match yellow, discovered that a few observers made matches that were very different from those made by the majority of other observers. There are many modern variants of this kind of test. The most frequently encountered design involves colors chosen so that the symbol is not seen by the color-defective observer (pseudo-isochromatic, falsely appearing of the same color). A symbol (number, letter, or geometric figure) composed of colored spots is set in a background of differently colored spots. The success of tests of this kind depends on the inability of color-defective observers to discriminate between certain colors. Pseudoisochromatic plates were first introduced by Stilling (1873). As a result, the Holmgren test is based on an erroneous and misleading set of color blindness categories and an unwise choice of test and match skeins. ![]() ![]() Although this position was subsequently abandoned by Helmholtz as erroneous, Holmgren adhered to it and selected three standard wool skeins (red, green, and purple) specifically to detect the three proposed types of color blindness. Helmholtz (1866) had tentatively proposed that color blindness could manifest itself in three forms-red, green, or violet blindness-depending on the missing type of color receptor (one for red, one for green, and one for violet). Holmgren's wool test is based on the principles of Helmholtz's theory of color vision. Variants of this test were devised by Holmgren (1877) using skeins of wool by Abney (1906), Oliver (1902), and Edridge-Green (1920) using small beads or pellets and by Fridenberg (1903) using small square pieces of colored cardboard. The task was performed by inspection and without color naming. The next advance in testing was made by Seebeck (1837), who required the observer to choose from a wide range of colored samples those that matched or most closely resembled a selected test sample. Dalton (1798) gave a detailed description of his own perceptions and those of his brother (both protanopes) and of some 20 other persons. This was the method employed by Turberville (1684) and by several subsequent investigators. One of the earliest methods used to test color vision was to compare the individual's color naming of everyday objects with that of a normal person. ![]()
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