The Critical Length is a Good Measure to Distinguish between Stick Balancing in the ML and AP Directions

Seven novice subjects participated in experiments of stick balancing on a linear track in the anterior-posterior (AP) and the medio-lateral (ML) directions. The goal of the experiments was to test how the depth perception in the subjects' AP direction affects balancing performance compared to balancing in the ML direction, where depth perception does not play a role. It is easier to balance longer sticks than shorter ones, therefore balancing performance is measured by the length of the shortest stick that subjects can balance. Subjects were found to be able to balance shorter sticks in the ML direction than in the AP direction: the ratio of the shortest stick lengths in the ML direction relative to the AP direction was in average 0.53. Thus, the additional challenge posed by depth perception in the AP direction is clearly observable. Additionally, repeated trials were carried out for 5 consecutive days to assess the development of balancing skill by using stabilometry analysis. The maximal balance time of the subjects significantly increased with the days of practice.