Spatial relationships between contours impact rapid scene classification

Photographs and line drawings of natural scenes are easily classified even when the image is only briefly visible to the observer. Contour junctions and points of high curvature have been shown to be important for perceptual organization (Attneave, 1954; Biederman, 1987) and have been proposed to be influential in rapid scene classification (Walther & Shen, 2014). Here, we manipulate the junctions in images, either randomly translating them, or selectively removing or maintaining them. Observers were better at classifying images when the contours were randomly translated (disrupting the junctions) than when the junctions were randomly shifted (partially disrupting contour information). Moreover, observers were better at classifying a scene when shown only segments between junctions, than when shown only the junctions, with the middle segments removed. These results suggest that categorizing line drawings of real-world scenes does not solely rely on junction statistics. The spatial locations of the junctions are important, as well as their relationships with one another. Furthermore, the segments between junctions appear to facilitate scene classification, possibly due to their involvement in symmetry relationships with other contour segments.