Alvarez George A, Franconeri Steven L
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
J Vis. 2007 Oct 30;7(13):14.1-10. doi: 10.1167/7.13.14.
Much of our interaction with the visual world requires us to isolate some currently important objects from other less important objects. This task becomes more difficult when objects move, or when our field of view moves relative to the world, requiring us to track these objects over space and time. Previous experiments have shown that observers can track a maximum of about 4 moving objects. A natural explanation for this capacity limit is that the visual system is architecturally limited to handling a fixed number of objects at once, a so-called magical number 4 on visual attention. In contrast to this view, Experiment 1 shows that tracking capacity is not fixed. At slow speeds it is possible to track up to 8 objects, and yet there are fast speeds at which only a single object can be tracked. Experiment 2 suggests that that the limit on tracking is related to the spatial resolution of attention. These findings suggest that the number of objects that can be tracked is primarily set by a flexibly allocated resource, which has important implications for the mechanisms of object tracking and for the relationship between object tracking and other cognitive processes.
我们与视觉世界的许多互动都要求我们将当前一些重要物体与其他不太重要的物体区分开来。当物体移动时，或者当我们的视野相对于世界移动时，这项任务就会变得更加困难，这要求我们在空间和时间上追踪这些物体。先前的实验表明，观察者最多能追踪大约4个移动的物体。对这种能力限制的一种自然解释是，视觉系统在结构上一次只能处理固定数量的物体，即视觉注意力方面所谓的神奇数字4。与这种观点相反，实验1表明追踪能力不是固定的。在低速时，有可能追踪多达8个物体，但在高速时，只能追踪单个物体。实验2表明，追踪的限制与注意力的空间分辨率有关。这些发现表明，可以追踪的物体数量主要由灵活分配的资源决定，这对物体追踪机制以及物体追踪与其他认知过程之间的关系具有重要意义。
