Factors contributing to differences in Rayleigh matches of normal trichromats

The Rayleigh match, a color match between 589 nm spectral light and an admixture of 545 and 670 nm lights, traditionally has been used as a test of defective color vision. Among normal trichromats, however, there is considerable variation in the range and midpoint of the Rayleigh match. The variation in normals’ Rayleigh matches was studied by measuring the matches of 20 observers on three repeated occasions. The left eye and right eye of each observer were tested at each session. These results assess the importance of five factors that might contribute to variation in normals’ matches: (1) differences among people in the match midpoint, (2) differences among people in the match width, (3) differences between the two eyes of the same person in the match midpoint, (4) differences between the two eyes of the same person in the match width, and (5) measurement error. The first three factors are shown to contribute significantly to differences in the matches of normal trichromats. The first factor accounts for most of the normal variation.