Figure 1.
Example of the stimulus arrangement adopted in the present study.
A pseudoisochromatic stimulus composed of circles of varying sizes and luminance is shown. The approximately square area with a different hue from background is the target.
Figure 2.
(A) Chromaticity points used as background. (B) Distribution of the 20 test vectors. The CIE 1976 u′v′ coordinates for each background chromaticity are presented. Also shown are the angle and dominant wavelength for each vector tested from the achromatic point (Background 1) of the CIE 1976 u′v′ chromaticity diagram. Negative values refer to vectors that contain “purples and magentas,” which are nonspectral colors and have no dominant wavelength but are described by their complementary dominant wavelength, lying on the opposite side of the diagram.
Figure 3.
Spectral sensitivity curves of L and M cone pigments from capuchin monkeys
. The maximum absorption peak of the visual pigments were predicted from the amino acid sequences from exons 3 and 5 of the X-linked opsin.
Table 1.
Genotype, absorption peak, and phenotype for each monkey.
Figure 4.
Example of staircases leading to threshold calculation.
The figures shows the sequences produced by a male monkey in a blue-yellow oriented vector (7) and red-green oriented vector (19). Each point represents the distance, in u′v′ units, between the chromaticity points that define the target and background. The distance was decreased following correct responses and increased following incorrect responses.
Figure 5.
Color discrimination thresholds obtained for capuchin monkeys.
The figure shows the thresholds obtained for 20 vectors around the achromatic point of the CIE 1976 u′v′ chromatic diagram (Background 1). The data were grouped according to the phenotypic classification derived from the genetic analysis.
Figure 6.
Discrimination ellipses obtained for capuchin monkeys.
The figure shows the best-fitting ellipses derived from the thresholds obtained in the 20 test vectors for each background. Deuteranopes are represented by data from subject M4.