Panel tests of colour vision such as the D15 and Farnsworth-Munsell 100-Hue tests are designed to classify people into broad categories of normal or deficient colour vision. Our interest lies in finer measurements within these categories. We apply the insights and methods of multidimensional scaling to individuals＇ performances on the D15 and 100-Hue tests, by interpreting these as information about the similarities between pairs of the test stimuli (16 and 85 stimuli, respectively). The results are quantitative descriptions of individual performances on the tests. There are implications for more objective test interpretations and diagnosis of colour-vision deficiencies. (C) 2000 John Wiley & Sons, Inc.