Thrice rice: Three studies in texture perception
Texture perception has important roles in vision. We have examined various aspects of texture perception in the following three studies: Long Range Interactions Between Oriented Texture Elements, Discrimination of Orientation-Defined Texture Edges, and Examining Edge- and Region-Based Texture Analysis Mechanisms. All textures used in the studies consisted of short, oriented line segments (texture elements) on gray backgrounds. In the first study we examined the influence of a background array of texture elements on the detectability of a target element (separated from the background by an intermediate region). We found that, in general, when the background elements were oriented orthogonally to the target element, detection of the target element was better than when the background elements had the same orientation as the target element. In the second study we examined discrimination performance for edges defined by texture elements as a function of the difference in orientation of the texture elements on each side of the edge. Texture elements on one side of the edge all had one orientation (say, 0$\sp\circ$), and texture elements on the other side of the edge all had a different orientation (say, 90$\sp\circ$). We found that discrimination performance improved (1) as the orientation difference (of the texture elements) across the edge increased, and (2) when the texture elements were parallel to (one side of) edge. In the third study we examined discrimination performance for textures which were intended to differentially affect edge-based and region-based texture analysis mechanisms. Each stimulus consisted of two textures which either abutted to form an edge or were separated by a blank region; each texture consisted of line elements with orientations chosen randomly using a Gaussian distribution (described by a mean and a standard deviation). We found that a texture difference in mean orientation led to superior discrimination performance when the texture abutted, but when the textures differed in the standard deviation of the orientation distribution, performance was similar in the two conditions.