研究发现在多目标追踪任务中，即使视野中的所有物体同时消失长达几百毫秒，被试也能成功地完成追踪任务。Horowitz等(2006认为这种能力主要是依靠把刺激消失时的目标信息保存在一种离线存储(off-line memory)记忆当中，这样当刺激再现时，被试就可以把当前画面与存储的内容进行比较来区分目标和非目标。本研究的目的在于探讨目标位置、运动轨迹和方向等信息在目标复原过程中的作用。结果发现:(1)目标再现位置与消失位置相同时，被试的成绩最好，这说明在目标复原过程中利用了基于位置匹配的策略。(2)当目标再现位置与其消失前的运动方向一致或位于其消失前的运动轨迹上时，成绩更好，这说明被试能够利用目标运动的轨迹和方向等信息。(3)当追踪的目标数量增加时，目标运动轨迹和方向等信息在复原过程中的相对作用下降;被试只能利用1—2个目标的轨迹和运动方向信息。

Several previous research have demonstrated that observers in multiple object tracking task can successfully track targets when all the objects simultaneously vanish for periods lasting several hundred milliseconds. Horowitz employed a switching hypothesis to explain this remarkable ability. To maintain the critical information of the tracking task, this hypothesis asks for a flexible off-line memory store. And in our experiment, we investigated whether location and trajectory information is involved in the off-line memory store and how do the observers use this information recovery the disappeared objects. We found that:(a).the observers tracked better when objects reappeared at their loci of disappearance than when they reappeared ahead or behind their original positions , which suggests a location-matching strategy in the recovery of disappearing objects. (b). Observers do better when the targets reappear on the previous trajectory, supporting the use of trajectory information in target reacquisition.(c). The trajectory and motion information being memorized deteriorates as the number of objects being tracked increases. It seems that trajectory and motion information is limited to 1-2 objects. All the results indicate that the visual system can maintain location, motion and trajectory information of the suddenly disappearing objects, but their role in reacquisition depending on the nature of the task.