Evidence for boundary-specific grouping.

A prerequisite for higher-level visual tasks such as object recognition is a segmentation of the image into distinct two-dimensional regions. While it has long been assumed that the human visual system jointly exploits region and boundary cues for image segmentation, we report the results of psychophysical experiments which suggest that the visual system relies on geometric properties of bounding contours such as closure and not on the texture of the two-dimensional regions they partition. These findings suggest that the visual system may code and links contours into coherent shapes before surface properties are conjoined.