Abstract
Crossing an obstacle requires visuospatial attetion (VSA) to identify the target in space so one can safely overcome the barrier without falling. In this study, we designed a VSA task that was embedded in an obstacle-crossing gait task to examine directly how these abilities interact. Seven subjects performed the VSA task projected on the floor during quiet standing and during obstacle-crossing gait task. The VSA task required the subjects to identify a briefly presented (500ms) stimulus (E or 3) among distractors (2s and 5s) within a visual display as quickly and accurately as possible. We positioned the stimulus at 1 of 9 locations around a circle (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, central). Each stimulus occurred five times in each location in a random order resulting in 90 trials in total. The obstacle was set to 10% height of the subject's height. As expected, the subjects performed the VSA task more accurately during quiet standing (87.76%) compared to obstacle crossing (79.80%). In addition, however, during the obstacle-crossing trials, accuracy in the VSA task was better for targets on the left-hand side of space compared to the right-hand side of space. Thus, the processes underlying VSA appear to be biased by the obstacle-crossing gait task.
