The possible elemental nature of brown

The continuous judgmental color-naming technique was used to assess the elemental nature of names descriptive of dark colors. Subjects were instructed to describe the color of a 0.54 deg. 2.5 log td test field of either 450, 530, 580 or 660 nm, that was surrounded by an achromatic annulus of 3.8 deg outer diameter. The annulus was varied in retinal illuminance from 1.5 to 3.7 log td. Test field and annulus were flashed simultaneously for 1 sec to the fovea of one eye. Results from 3 subjects indicated that the names blue, green, red and black were necessary and sufficient for describing the 450, 530 and 600 nm test fields. The 580 nm test field required the color name brown, in addition to the names yellow and black, to describe it when intermediate surround intensities were used. Additional results suggested the possible elemental nature of the color name brown.