Abstract

Consider a display containing many elements, among which there is a single critical target, differing slightly from the others, for which a subject is instructed to search. If a very small spatial detail defines this difference, (a) fixation near the critical target will be required for its identification, (b) a serial search will be needed to find it, and (c) the larger the number of targets, the longer will be the average search time needed to discover the critical target. The search time can be reduced if: (a) targets are color coded, (b) some of the targets are of an irrelevant color, and (c) the subject knows the color of the critical target. As Green and Anderson (1956) first put it, "When Os know the color of the target, search time is approximately proportional to the number of symbols of the target's color." Their seminal research, involving only two colors, has subsequently been extended to five by the work of Smith (1962).

© 1989 Optical Society of America