여러 개의 움직이는 시각 표적자극을 동시에 추적해야 하는 과제에서, Alvarez와 Cavanagh (2005)는 표적자극들이 양쪽 시각장에 각각 분배되어 제시되는 경우가 한 쪽 시각장에 모두 제시되는 경우보다 다중 표적자극들을 더 잘 추적함을 보임으로써, 복수의 움직이는 표적자극을 추적하는데 사용되는 주의 자원이 시각장에 따라 독립적으로 존재함을 주장하였다. 본 연구에서는 추적해야할 시각 표적자극들이 시각장 내 혹은 간 이동하는 경우, 추적 주의 자원이 이들 표적자극을 따라 함께 이동할 수 있는지 여부를 조사하였다. 만일 각 시각장에 할당된 주의 자원이 표적자극을 따라 이동할 수 있다면, 처음에 좌․우 시각장에 제시되었던 표적자극들이 하나의 시각장으로 이동된 후에도 추적 수행에 어려움을 보이지 않아야 할 것이다. 두 개의 실험에서 참가자는 여덟 개의 자극 중 네 개의 표적자극을 추적하는 과제를 하였다. 실험 결과, 표적자극들이 양쪽 시각장에 각각 두 개씩 제시되었다가 양쪽 시각장을 유지한 채 이동하는 조건에서의 추적 정확률이 처음 표적자극이 양쪽에 제시되었다가 한쪽 시각장으로 이동하는 조건의 정확률 보다 유의미하게 높았다. 이 결과는 각 시각장에 할당된 추적 주의자원이 다른 시각장으로 이동한 표적자극을 따라 함께 이동하기 어려운 것으로 해석할 수 있다.
Alvarez and Cavanagh(2005) have reported that there are independent attentional resources for multiple object tracking (MOT) in two hemifields. Twice as many targets could be successfully tracked when they were distributed between hemifields as when they were all presented within a single hemifield. We investigated whether the attentional resource for tracking in one hemifield could track the targets that were presented initially in that hemifield, but later moved to the other hemifield. In our experiments, the participants tracked four objects among eight objects. The four targets were divided equally between the left and right hemifields. In one condition, targets moved only within each hemifield in which they were initially presented (Bilateral-to-Bilateral condition). In the other condition, two targets in one hemifield moved toward the other hemifield, while the other two targets remained moving in the initial hemifield, resulting in four moving targets within a hemifield(Bilateral-to-Unilateral condition). Our main interest was comparison between these two conditions, measuring the accuracy of MOT. The results showed that performance in the Bilateral-to-Bilateral condition was better than that in the Bilateral-to-Unilateral condition. In other words, when the initial targets presented in one hemifield moved across to the other hemifield, the attentional resource in each hemifield did not move cross the other hemifield along with the moving targets. This finding suggests that attentional resource for tracking could be object-based only within each hemifield.
Alvarez and Cavanagh(2005) have reported that there are independent attentional resources for multiple object tracking (MOT) in two hemifields. Twice as many targets could be successfully tracked when they were distributed between hemifields as when they were all presented within a single hemifield. We investigated whether the attentional resource for tracking in one hemifield could track the targets that were presented initially in that hemifield, but later moved to the other hemifield. In our experiments, the participants tracked four objects among eight objects. The four targets were divided equally between the left and right hemifields. In one condition, targets moved only within each hemifield in which they were initially presented (Bilateral-to-Bilateral condition). In the other condition, two targets in one hemifield moved toward the other hemifield, while the other two targets remained moving in the initial hemifield, resulting in four moving targets within a hemifield(Bilateral-to-Unilateral condition). Our main interest was comparison between these two conditions, measuring the accuracy of MOT. The results showed that performance in the Bilateral-to-Bilateral condition was better than that in the Bilateral-to-Unilateral condition. In other words, when the initial targets presented in one hemifield moved across to the other hemifield, the attentional resource in each hemifield did not move cross the other hemifield along with the moving targets. This finding suggests that attentional resource for tracking could be object-based only within each hemifield.