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 under conditions of global or local attention. It was hypothesized that thresholds in global attention would be lower than in local attention. Methods: Eleven adult subjects participated in this study. Subjects were required to identify direction of motion at variable coherence levels. 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; however thresholds were significantly higher at 18 degrees/s than in the lower velocities. Conclusions: These results highlight the attentional limitations of visual information shown by increased motion coherence thresholds when two objects must be identified simultaneously in a brief display.