自由拦截启动策略与信息利用

手的启动方向自由, 伸手拦截不同速度的运动小球。本研究通过考察手启动时的运动参数, 研究自由启动的情况下的信息利用和拦截策略, 并且考察了人的启动模式。结果发现, 自由拦截时手的拦截区域相对固定, 在物体快速运动情景下启动晚, 而在慢速下启动早, 可能综合利用了接触时间和距离信息, 存在速度伴随效应, 手的拦截启动策略为启动有相对稳定的角度和加速度, 并不随物体运动速度和物体大小的改变而改变。

The Role of Information and Movement Pattern in the Onset of Free Hand Interception

Interception is a specialized sequence of visual guided actions that occurs when human hands or other body parts initiate an approach to opposing moving target and finally catch them at a certain spatial location. When humans can decide the interception direction of the hand and the time of the startup, what kinds of information do they use to start the interception? It is difficult to estimate time-to-collision (TTC) because the interception zone is not certain. The first aim of the present study was to investigate the role of temporal information and spatial information in hand interceptions of a moving target. In addition, the speed coupling effect has been explained by different and inconsistent theories. The second aim of this study was to examine whether or not this phenomenon existed in free interception and whether or not there was any particular identifiable movement pattern in the interception. Fifteen undergraduate students participated in the experiment. All of them had normal vision or vision correction to normal. The experiment’s program was run on a Dell computer using Borland C++ Builder. Subjects were asked to hit the moving ball using their index fingers along linear. The tracks of the subject’s hand were recorded by a movement-analysis system based on active infrared markers (Optotrak 3020; Northern Digital). The program also recorded the position of target ball (startup point) when the hand started to move and the distance between the startup point and the interception point when the finger hit the ball. All of the dependent variables were analyzed with repeated measure ANOVA. The results showed that (1) Different velocities of the target ball influenced the distance and time to collision differently. Time to collision was shorter if the target ball moved more quickly, and it was longer when the target ran more slowly. (2) The startup direction and acceleration of the hand were not affected significantly by the velocity of the target ball. The results did identify a specific movement pattern in the startup of interception. The conclusions are directed by the study: There is fixed area in interception. It appears that tau and distance may both be used in startup. The speed coupling effect is related to the error of the estimate. The direction and acceleration are stable when subjects start intercepting.