Changes of Multiple Object Tracking Performance in a 15 Days’ - 6° Head-Down Tilt Bed Rest Experiment

Abstract

Human-computer interface (HCI) design should fully consider the basic human visual ability including multiple object tracking (MOT). A MOT test was conducted in a 15 days’ - 6° head-down tilt bed rest (HDTBR) experiment to investigate effect of weightlessness environment on MOT performance. During 15 days’ HDTBR, subjects were asked to stay in bed and hold the specific postural all the time even when they were being tested, taking meals and relieving themselves. A computer program which lasted for about 25 min to measure the MOT performance was used. MOT performance was represented by the selection accuracy. MRM ANOVA results showed that the main effect of the number of target balls was significant (P < 0.001) and the main effect of test time was significant (P = 0.002). Back testing of paired test showed that the selection accuracy of 4 target balls (79.324 ± 3.147) was higher than selection accuracy of 5 target balls (70.918 ± 3.175) and selection accuracy of 6 target balls (66.118 ± 2.715) significantly (P < 0.001). Also the selection accuracy of 5 target balls was higher than selection accuracy of 6 target balls significantly (P = 0.002). The above results means that when the number of tracking targets is from 4 to 6, the smaller the number to be tracked, the higher the tracking performance. In addition, selection accuracy after 13 days’ HDTBR (75.840 ± 3.113) was highest than others and was higher than selection accuracy at one day before HDTBR (68.857 ± 2.602) and 3 days’ HDTBR (71.206 ± 2.351) significantly (P = 0.008, P = 0.043), which means best tracking performance appeared after head down tilt bed rest 13 days in the experiment. The weightlessness environment may improve the performance of MOT by some mechanism.