Abstract
We examined individual differences in red, yellow, green, and blue unique hue loci with nonspectral lights and sought possible correlation between unique hue settings, Rayleigh match midpoints, and the individuals' favorite colors. Data were gathered from twenty-three normal trichromats (five male and 18 female, ages 18–23 with mean of 19.4). First, three Rayleigh match settings were obtained by the method of adjustment, using the Neitz anomaloscope OT-II. Second, the observer stated his/her three favorite colors. Third, the four unique hue loci were measured using the two randomly interleaved staircase method on a Sony GDM-F520 color display controlled by Radius ThunderPower 30/1600 video card and Macintosh G4 computer. In each trial, the test field of a 2°×2° square was presented for 500 ms in the center of the white (Illuminant C) surround. The chromaticity of the test field was changed on the equiluminant plane in the DKL space maintaining the maximum contrast. We found a correlation between unique blue and unique green loci. Larger hue angles in unique blue were associated with the larger hue angles in unique green. We also found a correlation between Rayleigh match and unique green. Some studies indicate this relationship among normal trichromatic males, but others deny such a relationship (Jordan & Mollon, 1995). ANOVA revealed a correlation between the first favorite color and the unique blue locus (F(7, 15)=2.888, p<.05). The observers who chose blue as their first favorite color tended to set the unique blue at smaller hue angles, indicating they require more S-cone stimulation to obtain the unique blue. This finding may imply that color appearance for an individual plays a role in shaping his/her preferred colors. Alternatively, both of these may be influenced by a common factor. Supported by NIH grant R15 EY13936.
Jordan, G. & Mollon, J. D. (1995). Rayleigh Matches and Unique Green. Vision Research, 35, 613–620.