The influence of shape and skeletal axis structure on texture perception.

We studied the relationship between texture orientation and shape skeletal axes in two tasks related to texture perception. The first series of experiments investigated discrimination of texture-defined shapes. We found that alignment between texture orientation and the skeletal axis of a figural region improved the segmentation strength, as did a perpendicular arrangement to a lesser extent. The alignment effect is attributable to the orientation of the skeletal axis itself, not the orientation of the figure edges; these two factors were deconfounded by the use of shapes whose contours undulated relative to the main axis orientation. Discrimination of multi-part shapes additionally showed that local alignment of texture with the axis of the enclosing part gave superior segmentation performance when compared to the classically optimal case of uniform texture orientation. A second series of experiments investigated sensitivity to changes in texture orientation within texture patches. Texture orientation discrimination was heightened when texture was aligned with the axis of the patch shape, demonstrating that the "axis effect" also affects the encoding of texture orientation. Taken together, these findings point to a broad role of skeletal axes in influencing the processes by which texture elements are aggregated to form the object itself.