Interference and dominance in texture segregation: hue, geometric form, and line orientation.

Five experiments were designed to test whether (1) lowering the similarity of elements within a region of texture (low-similarity arrays) would interfere with texture segregation, and (2) there would be dominance of one type of property difference over another in determining an observer's choice of boundary in two-boundary (ambiguous) displays. In Experiments 1 and 2, the interference question was assessed using stimuli formed from the dimensions hue and geometric form (circle/square or straight/curved novel shapes). The results indicated that when boundary judgments were based on form differences, segregation was significantly impaired by hue variation. However, hue segregations were not affected by form variation. In Experiments 3-5, the dominance question was examined using stimuli formed from hue and geometric form, as well as those formed from hue and line orientation (horizontal/vertical). Analyses revealed that there was no dominance of one type of property difference over another. Rather, observers' performance was completely predicted by the relative discriminabilities of the two boundaries. These findings support Beck's (1982) model of textural segmentation and call into question traditional notions of the preattentive stage of perceptual processing.