Different Methods of Visual Cognitive Memorization of an Obstacle Affect the Results of a Stepping Over Task

The purpose of this study was to clarify the influences of three different conditions on the task accomplishment of stepping over an obstacle: the difference of the distance of the obstacle in visual cognitive memory and the actual obstacle, the time difference in memorization from memorization in the stationary state and mobile state walking towards the obstacle. After being given 5 seconds under six conditions to memorize the obstacle in visual cognitive memory, 25 healthy students stood in front of the obstacle, and stepped over it gazing at a target in front of them. They were recorded on video, and the center of pressure of the footstep after stepping over the obstacle was measured using a force plate. We did not find significant differences in the footstep center of pressure and distance of obstacle-foot position between the stationary and mobile states. However, stepping over the obstacle straight after memorization showed a significantly shorter stride over the obstacle and the center of pressure tended to be more stable than after 15 seconds. Furthermore, in stepping over the obstacle in the stationary state, in the near condition the foot was placed closer to the obstacle than in the far condition. However, in mobile state walking toward the obstacle, there were no significant differences between the near and far conditions; in the near condition the closeness of the obstacle to the foot stepping over it became obscured by the approach. From these results, in stepping over something when the obstacle is close, we can recognize the obstacle properly with the sense that we can actually step it over, and it is also suggested that if the interval from memorization in visual cognitive memory was short, we could step over the obstacle more appropriately and economically. It was considered that approaching the obstacle from the far position contributed to improved appropriate visual cognition of the obstacle.