MOTION PERCEPTION IN GLOBAL VERSUS LOCAL ATTENTIONAL MODES

Purpose: Global and local attention are two forms of selective visual attention which activate different areas of the cortex. The purpose of this experiment was to test subjects' motion coherence thresholds und er conditions of global or local attention. It was hypothesized that t hresholds in global attention would be lower than in local attention. Methods: Eleven adult subjects participated in this study. Subjects we re required to identify direction of motion at variable coherence leve ls. while simultaneously identifying either the global or local letter . Three velocities were used for coherent motion (3, 6 and 18 degrees/ s). Results: The results showed that letter identification (global or local) did not significantly affect motion coherence thresholds; howev er thresholds were significantly higher at 18 degrees/s than in the lo wer velocities. Conclusions: These results highlight the attentional l imitations of visual information shown by increased motion coherence t hresholds when two objects must be identified simultaneously in a brie f display.