OBJECT CONTINUITY IN APPARENT MOTION AND ATTENTION

Recent theories of attention have emphasized the role of object-based representations in visual selection. One defining property of any obje ct is spatiotemporal continuity. The present experiments show that the continuity property may underlie two seemingly unrelated perceptual p henomena: attentional capture by abrupt visual onset and the appearanc e of bistable apparent motion displays. In Experiment 1, observes carr ied out two visual tasks. In the first task, they reported the appeara nce of a bistable apparent-motion (or Ternus) display. Whether group o r element motion was perceived depended on the duration of the blank i nterval between successive frames. In the second task, subjects engage d in visual search for a prespecified target, and on each trial one el ement was briefly flickered off and back on. The degree to which that element captured attention also depended on the duration of the tempor al gap. The time course of the gap duration effect in the visual searc h task was very similar to that for the Ternus display. In Experiment 2, we ruled out the possibility that die presence of an abrupt offset caused the results of Experiment 1. It is argued that the apparent mot ion and attentional capture phenomena examined here may reflect the op eration of the same underlying mechanism: in both cases, a sufficientl y long temporal gap disrupts spatiotemporal continuity, thereby fundam entally changing the perceived organization of the display.