Visual sensitivities to color differences were determined for four colors in the presence of five surrounding fields. The colors matched were red, green, blue, and white. The surrounding fields were successively red, green, blue, white, and black. Color-discrimination ellipsoids were determined for the above conditions for matching fields subtending 12 degrees and 2 degrees. Large visual fields allow better color discrimination than fields covering only the foveal region. For small matching fields, discrimination is reduced by surrounding fields of different color. With large (12-degree) matching fields, color discrimination is relatively independent of the surround.
W. R. J. BROWN, "The Effect of Field Size and Chromatic Surroundings on Color Discrimination," J. Opt. Soc. Am. 42, 837-843 (1952)