Color category influences heterogeneous visual search for color.

Many previous studies have revealed chromatic characteristics of visual search using relatively simple stimuli. They suggested that color difference between a target and distractors was a crucial factor. However, it may not be applicable to natural environments that contain numerous colors. This study demonstrates the existence of a color-category effect on heterochromatic visual search. Color differences between a target and distractors were constant in the OSA uniform color scales; however, the search times varied widely. This suggests that color differences alone do not explain search performance. To clarify the mediation of a higher-order categorical color process, search times were analyzed using 11 basic colors. When the color category of a target was shared by a larger number of distractors, the search performance declined. However, when the color category of a target was not shared with distractors, the target was easily detected. The results suggest that heterochromatic stimuli could be segregated by categorical color perception.