Visual search in natural scenes explained by local color properties.

Success in visually searching for a small object or target in a natural scene depends on many factors, including the spatial structure of the scene and the pattern of observers' eye movements. The aim of this study was to determine to what extent local color properties of natural scenes can account for target-detection performance. A computer-controlled high-resolution color monitor was used to present images of natural scenes containing a small, randomly located, shaded gray sphere, which served as the target. Observers' gaze position was simultaneously monitored with an infrared video eye-tracker. About 60% of the adjusted variance in observers' detection performance was accounted for by local color properties, namely, lightness and the red-green and blue-yellow components of chroma. A similar level of variance was accounted for by observers' fixations. These results suggest that local color can be as influential as gaze position in determining observers' search performance in natural scenes.