Hue-discrimination in normal colour-vision

Hue-discrimination curves have been obtained for five normal observers; the apparatus and method of observation are described and the results discussed. Two minima in the discrimination curve are found at about 0.60 μ. and 0.49 μ. and a secondary minimum at 0.45 μ. The curves are appreciably different from those normally reproduced in text-books, particularly at the red end of the spectrum where a secondary minimum has generally been shown. An analysis of the work of previous investigators, however, shows that the evidence for this secondary dip is very inconclusive.