Motion and shape in common fate

We determined how much motion coherence was needed to detect a target group of four moving dots in a dynamic visual noise (DVN) background. The lifeti mes of the trajectories of the target and that of the noise dots were the s ame. In addition to parallel trajectories and collinear dot arrangements, d ivergent, convergent, or crossing trajectories and non-collinear dot arrang ements were also tested. Performance saturated at a lifetime of approximate ly 600 ms. It was best for parallel trajectories and collinear dots, and wo rse for crossed trajectories with noncollinear dots, where it approached pe rformance in a no-motion, form-only control experiment. Results illustrate the importance of common fate in motion perception in DVN, when other facto rs are equated. (C) 2000 Elsevier Science Ltd. All rights reserved.