SALIENCY FROM MOTION AND FORM COMBINED
Detectability of an element with a trajectory composed of many small jumps is enhanced relatively to the detectability of individual motion (2 frames), more when the trajectory is straight than when it changes direction by a small amount each frame (Watamaniuk, McKee & Grzywacz, 1995). We asked whether enhancement is higher with line-segments oriented in the direction of motion (iso-motion) or orthogonal to it (ortho-motion). At high curvature (where successive presentation of motion signal are not co-axial), we found higher saliency for ortho-motion, suggesting that saliency in texture segmentation is accounted by the orthogonal velocity component (V). However, at small jittering, saliency of iso- and ortho-motion did not differ, suggesting that when the two saliency mechanisms (responding either to co-axiality or to V) are both activated, they compete for salience.