Textural effects in perceived pointing of ambiguous triangles.

Five experiments examined the influence of textural stripes on perceived pointing of ambiguous (equilateral) triangles. Reaction times for discriminating specific directions of pointing were measured for plain triangles and for triangles containing stripes that were either coincident with or perpendicular to one of the three possible directions of pointing. Perceptual interference occurred when the stripes biased a direction other than one specified by the discrimination task. The magnitude of the interference decreased (a) as the environmental salience of the specified direction increased and (b) as the spatial frequency of the stripes increased. Further results indicated that this frequency effect is relative to the size of the triangle; it is not determined by absolute (retinal) frequency. Stripes in the ground region surrounding the triangle also produced interference. However, this interference decreased as the region around the triangle was cleared of stripes. The results are discussed in terms of factors that determine the qualitative and quantitative nature of the interference effect, particularly symmetry and spatial frequency.