ACUITY OF DISCRIMINATION

There is a collection of colors, known as the Farnsworth-Munsell Test (Farnsworth, 1949), consisting of 86 chips of equal brightness and saturation but differing in hue. These colors were chosen by the authors of the test so as to constitute an instrument for the testing of hue discrimination. Subjects are presented with two chips, say one green and one blue, and are asked to put a disarranged collection of shades between these two colors into the proper order so that an array results with all chips finely graded from green to blue. Similar tasks are required with shades between blue and purple, purple and red, and red and green. When the test is administered to a noncolor-blind standard population of young American adults, a certain average number of sorting mistakes occur, but the mistakes occur with equal likelihood anywhere in the spectrum (and the mistakes for any one color chip have a frequency distribution that is the same for all colors).

The question now arises whether the construction and standardization of the test might have been biased by the language habits of its authors who were English speaking individuals. Since the color vocabulary superimposes a classification upon the physical color continuum might it not have predisposed us to pay more attention to the borderline cases, thus sharpening our acuity across wordclass boundary, and to pay relatively less attention to the clear-cut cases, thus dulling our acuity within the word classes?

Lenneberg and J. Bastian (unpublished data) administered the Farnsworth- Munsell Hue Discrimination Test to a group of Zuni and Navaho Indians whose color vocabulary had been mapped into the stimulus continuum by Lenneberg and Roberts (1956) and Landar et al. (i960) respectively. The different locations of the Zuni and Navaho color-name boundaries did not predict in either case systematic difference in discriminatory acuity between the Indians and a control group of Anglo-American farmers living in the same region. Thus there is little ground to assume that the peculiarities of English color words have affected the construction of the Farnsworth-Munsell Test in any basic way.

There is, however, another type of evidence that may cause us to reconsider our conclusions. Beare (1963) elicited English color words for a series of monochromatic lights. Here stimulus material had the advantage of being perfectly controlled in its physical properties and each color could be specified in terms of wavelength. She required subjects to name every stimulus presented as red, orange, yellow, green, blue, violet and to make the response as fast as possible. After an appropriate decision had been made the subject was allowed to qualify the name given by further adjectives. If a stimulus fell within a name map the response was made relatively quickly and few or no qualifiers were used. A stimulus that fell between maps had a longer response latency and elicited a greater number of qualifiers. Thus, she used Approach B to map words into the particular referent space represented by her stimuli.

Beare used a slightly different procedure to compare her naming data with Judd’s acuity data, but she was generally skeptical about a causal relationship between the two. In her own words: ‘ what fit there is between the two functions is tenuous, and it is possible that the configuration of the naming curve will change (if a different stimulus array is used), or with changes in instructions with regard to categories of judgment ’. Even if Beare shall eventually be proved to have been too modest in her conclusions, we can still not be certain whether the name boundaries of the English words are entirely arbitrary; only if other languages can be shown to have markedly different boundaries for this particular stimulus array and if the speakers distribute their loci of greatest acuity in a predictable direction may we conclude that non- physiological factors have affected hue-discrimination. For the time being, we must withhold judgment.