MOTION INTERFERENCE - PERTURBING PERCEIVED DIRECTION

The minimum stimulus necessary to define motion is a change in positio n from one location to another in time, but past studies have provided evidence that the human motion system integrates motion over more tha n two positions. In this study we demonstrate strong sequential intera ctions affecting perceived direction in apparent-motion sequences; a p erturbing dot can bias the perceived direction of motion between two t est dots to which it is relatively close in space (up to 100 min arc) and time (up to 300 msec). These sequential interactions suggest a mot ion mechanism sensitive to the spatial characteristics of motion traje ctories; the interactions are greatest for evenly spaced targets posit ioned along a single axis. The implications for motion-detection model s and models based on attention as a mechanism to create apparent moti on are discussed. (C) 1997 Elsevier Science Ltd.