Effects of priming in texture segmentation

This study aimed at establishing whether, as follows from the perceptual representation system (PRS) hypothesis, mechanisms for coding configural properties in texture segmentation are similar in perception and short-term perceptual memory (STPM). We investigated whether implicit STPM for a texture bar oriented 45° clockwise or counterclockwise produced different priming effects on texture segmentation, depending on whether bar orientation was parallel or orthogonal to its line texture elements. Orientation discrimination in the first block was at threshold (74%) for parallel but not for orthogonal (40%) bars. Training brought all performances to ceiling, suggesting that training makes parallel and orthogonal bars equally salient. However, performance was worse when the stimulus in the nth trial was preceded by a parallel bar rather than an orthogonal one, regardless of whether the bar in the nth trial was parallel or orthogonal; this (priming effect) decreased with training. These results indicate that in the first trials the parallel, more salient, bar is coded in the PRS by low-spatial-frequency mechanisms selective to the whole-bar orientation, and that this STPM may interfere with local texture segmentation. On the other hand, the orthogonal, less salient, bar is coded in the PRS by high-spatial- frequency channels selective for texture elements or texture borders and interferes less with texture processing. Learning equates salience of parallel and orthogonal bars so that the memory code, as well as the sensory processing, become similar for the two kinds of texture. These findings support the view of a common mechanism (namely, PRS) responsible for visual processing and STPM of visual stimuli, which operate at early levels of the visual stream.