The Role Of Temporal And Spatial Information In Intercepting Moving Targets

Interception is a specialized sequence of visual guided actions that occur when human hands or other body parts initiate to approach the opposing moving targets and finally catch them at a certain spatial location. Reaching an appropriate location just in time makes a successful interception, which takes a bundle of related topics such as perception, movement control and time estimation into account. The studies on interception of moving targets could not only contribute to the psychology itself, but also shed light on other related domains such as automation, aviation technology, traffic safety and Artificial Intelligence. The study aimed to explore how temporal and spatial information were used to fulfill an interception of a moving target.The work consisted of two sub researches.The effects of the temporal and spatial information on the start-up of interception were examined in the first research, which included three experiments. In the first experiment, a simulated perception task of interception was employed, and subjects were instructed to press a button to release a uniform motion ball for interception. An action task was included in the second experiment, in which the direction of interception was fixed, but the velocity of hands could adjust freely. In the third one, subjects could freely control both the velocity and direction of their hands. The results suggested that both the temporal and spatial information were used in the interception start-up. Specifically, subjects started interception earlier when the target moved more slowly. On the contrary, interception onset was later when the target moved faster. These results did not favor the attempts to account interception start-up solely withτhypothesis. The second research, with another suite of three experiments, focused on the use of temporal and spatial information during the interception. The roles of such information on the hand movement were explored by eliminating available spatial information or building a scenario where the spatial information was not consistent with the temporal information in the fourth experiment. In the fifth one, memory tasks were added to delve into the processing mechanism of temporal and spatial information as well as their impact on the interception. In the sixth experiment, the use of information was examined in different reaching phases. It was found that both temporal and spatial information were used in early phase, but only the temporal information was extracted during middle and late phases. The spatial information was processed automatically, while temporal information was controlled. The results were consistent with the hypothesis of plan-control model. The previous models that emphasized temporal information might be limited.Besides, a new interpretation of speed coupling effect was put forward. Exposed to the temporal and spatial information, subjects were prone to underestimate TTC (time to contact) of the slowly moving targets. In contrast, they overestimated TTC of fast moving targets. Thus the time of hand movement was relatively shortened in the interception of fast moving targets. Furthermore, the startup acceleration of hand varied with the startup directions of hand. In a particular direction, the startup acceleration of hand varied with the speed of the target too. However, the changes in acceleration tended to neutralize when the speed of targets exceeded the middle range. On the other hand, the startup direction and acceleration were invariable when hand moved freely, and were not changed with the speed of targets. It was indicated that there was likely an ideal pattern of hand start-up in interception tasks with proper acceleration and direction in the free movement situation.