MOTION TRANSPARENCY ARISES FROM PERCEPTUAL GROUPING - EVIDENCE FROM LUMINANCE AND CONTRAST MODULATION MOTION DISPLAYS

What circumstance lead to the perception of global motion transparency ? It has been shown that, in paired random dot displays, motion transp arency can be abolished if the separation of the dot pairs is sufficie ntly small [1]. Motion transparency has also been shown to be influenc ed by high level cognitive cues [2]. Here, we report that the combinat ion of two moving dot stimuli, which separately invoke a percept of tr ansparent motion, gives rise to a non-transparent percept of local rot ation. These stimuli were constructed using various different pattern elements, including luminance defined elements and contrast modulation s. The results extend and support the view that high-level grouping of local measures of the velocity field can determine whether a motion t ransparency is perceived or not. (C) Current Biology Ltd ISSN 0960-982 2