PREFERENTIAL PROCESSING OF TARGET FEATURES IN TEXTURE SEGMENTATION

In five experiments, observers were required to detect a texture targe t and/or identify the orientation of elements composing target and non target regions. They were significantly worse at discerning the orient ation of nontarget regions than at detecting target presence (Experime nt 1). On the other hand, accuracy of identifying target orientation w as found to be near 100% (Experiment 2). When observers were required only to identify surround orientation (Experiment 3), accuracy was dim inished on target-present trials relative to that on target-absent tri als. The superiority of target processing and the interference produce d by target presence on surround processing were demonstrated in unpra cticed observers (Experiment 4). In Experiment 5, it was found that in formation regarding target presence is available before information re garding feature values of the target. These findings are consistent wi th a model of visual attention and search that incorporates a fast gen eralized difference operator and a slower feature comparison process.