The Influence Of Gravity On The Direction Effect Of Speed Perception

Speed perception means the individual estimates and judges the speed of moving objects by humans’ visual information. It is the combination of visual perception and time perception. Speed perception significantly affects many things such as the driving safety of the drivers, the performances of athletes and the individual’s avoidance action of the collision. “The direction effect of speed perception " refers to the phenomenon that human beings differs in the speed perception between horizontal movement direction and vertical movement direction. Whether the direction effect of speed perception exists? Whether the direction effect of speed perception is affected by gravity conditions? What can lead to the appearance of the direction effect of speed perception and what is the internal mechanism behind this effect? This research aims to find out the solutions to these questions.This study consists of three parts. In the first study, we try to explore whether the direction effect of speed perception exists.And we also want to know whether the direction effect of speed perception changes under different gravity conditions. In the second study, we aims to find out the internal mechanism of the direction effect of speed perception. By adopting the method of separately investigating line segment and time span, we observe and compare the line segment estimation and time span estimation changes under different gravity conditions. In the third study, we made validity research of the direction effect of speed perception to explore whether the direction effect of speed perception keeps the tendency when the speed and visible distance increase. At the same time, we also can figure out whether the changing tendency of the direction effect of speed perception affected by speed and visible distance under different gravity conditions.The main conclusions of this study are as follows:1. In the ground experiment, the direction effect of speed perception will appears when the speed is low and medium controlled between 50 to 100 pixels per second. In the normal gravity condition, the speed perception biases in the vertical direction exceeds the speed perception biases in the horizontal direction. The effect is significantly obvious especially when the speed is 50 pixels per second.2.Gravity conditions can affect the existence of the direction effect of speed perception. But the direction effect of speed perception shows a fading trend under the weightlessness condition.3.In the normal gravity condition, the line segment horizontal-vertical illusion appears. However, the difference degree of the line segment horizontal-vertical illusion weakens and even disappears in the weightlessness condition. And this phenomenon is the internal reasons why the direction effect of speed perception weakens under the weightlessness condition.4.Only when the object shows low speed movement and individuals can fully observe the target object visible movement trajectory can the direction effect of speed perception weaken under the weightlessness condition.5. The speed perception characteristics of humans is affected by gravity conditions. Compared to the speed perception biases under the normal condition, individuals present a growing trend of speed perception biases under the weightlessness condition.