Objective: Individuals maintain a spatial margin or 'personal space' between themselves and others. The form of this space and strategies for avoiding obstacles can be influenced by participant characteristics such as age. In this study, we investigated the characteristics of personal space and obstacle avoidance strategies in young and older adults. We also examined differences in perceptual personal space and walking trajectory during obstacle avoidance using a three-dimensional motion capture system. Methods Ten young adults and ten older adults participated in this study. We calculated actual obstacle avoidance trajectory and obstacle avoidance data such as the lateral spatial margin and body rotation angle during walking in a task that included obstacle avoidance. We also measured the perceptual personal space created by approaching a confederate. In order to calculate each personal space and obstacle avoidance data, we used a three-dimensional motion capture system. Two factors (two groups and personal space) of repeated analysis of variance were used in statistical analysis. Results We found no age-related differences in personal space or obstacle avoidance strategy in this study (F = 0.52, p = 0.48). However, we found significant differences in the form of perceptual personal space and personal space formed during obstacle avoidance (F = 11.86, p = 0.0030). Conclusion This study indicates that perceptual personal space did not reflect the walking trajectory created by actual obstacle avoidance. In addition, age did not influence the obstacle avoidance strategy. These results suggest that the perceptual personal space and aging have little effect in the situation of avoiding a single standing pedestrian.

[Purpose] The purpose of this study was to determine the change of allocation of attention caused by a difference in gait phase and gait speed. We also determined the relationship between attentional demand and gait automaticity change caused by the gait speed alteration. [Subjects and Methods] Ten male participated. Participants were instructed to perform the probe reaction time (RT) task during treadmill walking in four different gait speed conditions (60%, 80%, 100%, and 120% of preferred speed). Walking ratio in each gait speed conditions were calculated, and RTs and walking ratios were compared in each gait speed condition and in the single-support and double-support gait phase. [Results] RTs were significantly delayed with decline of gait speed. Walking ratio was significantly decreased in proportion of decrement of gait speed. There was no difference of gait phase between single-support and double-support phase. [Conclusion] This study showed that relationship between attentional load and deficit of gait automaticity. While gait phase didn’t influence attentional demand, and this result showed the characteristics of treadmill gait.