Educational and Psychological Measurement

Abstract

framed, and it would be difficult to add anything appreciable to them. It is interesting to note, however, that Titchener, having reviewed the evidence and taken his stand, says that we would all welcome a crucial experiment. It would be worthwhile, I believe, to study the methods of describing color as a function of the mode of appearance, and to search for pertinent stimulus-variables and functions of them correlating with reports of the colors by direct visual estimation. Such a study would constitute a whole series of crucial experiments. Let all abstractions, including those of black and white sensations, be tested for usefulness in color description for all modes of appearance. On this account, we should watch with particular interest the further development of Professor Dimmick's proposal to specify color in all modes of appearance by the seven primaries: red, yellow, green, blue, white, gray, and black, taken four at a time, two chromatic and two achromatic.31 In the meantime, the tentative definition of black and white with which this note was introduced may as well be taken. Its usefulness is exemplified by the psychophysical relation given in Equation [2), and its validity has not been questioned by anyone. Whether it be possible to extend with similar validity and usefulness the definition of black and white to modes of appearance other than surface remains to be decided by further study. National Bureau of Standards DEANE 8. JUDD Washington, D.C.