Calculate (Don't Guess) the Effect of Symbol Size on Usefulness of Color

Everyone knows that the colors of smaller objects are less distinct than the colors of larger images. This fact is of practical importance in the design of visual display formats. Color is useful to speed visual search and to organize categories of information. Because display space is precious, symbols are made as small as possible. The display designer must make a tradeoff between symbol size and operator performance. The purpose of this paper is to provide a quantitative basis for the tradeoff. Methods to calculate the effect of symbol size are evaluated, design tricks are highlighted, and the reader is alerted to pitfalls.