Niebergall Robert, Huang Lawrence, Martinez-Trujillo Julio C
Cognitive Neurophysiology Laboratory, McGill University, Montreal, Quebec, Canada.
J Vis. 2010 Oct 1;10(12):4. doi: 10.1167/10.12.4.
Visual-spatial attention enhances the perception of behaviorally relevant stimuli. One issue that remains unclear is whether attention is preferentially allocated to stimuli that remain fixed in one reference frame (e.g., retina-centered), or whether it could be equally allocated to stimuli fixed in other frames. We investigated this issue by asking observers to covertly attend to sinusoidal gratings fixed in different reference frames and to discriminate changes in their orientation. First, we quantified orientation discrimination thresholds (ODTs) while subjects pursued a moving dot and either attended to a retina- or a space-centered grating. We then measured ODTs while subjects divided attention between the two gratings. We found that dividing attention proportionally increased ODTs for both target gratings relative to the focused attention condition. Second, we used the same stimulus configuration and conditions during a fixation task. Here, one grating was retina- and space-centered while the other moved in space and on the retina. Again, ODTs during divided attention proportionally increased for both gratings. These increases were similar to those measured during smooth pursuit. Our results show that humans can proportionally divide attention between targets centered in different reference frames during both smooth pursuit eye movements and fixations.
视觉空间注意力可增强对行为相关刺激的感知。一个尚不清楚的问题是，注意力是否优先分配给在一个参考系（如以视网膜为中心）中保持固定的刺激，或者它是否可以同样分配给在其他参考系中固定的刺激。我们通过要求观察者 covertly 关注固定在不同参考系中的正弦光栅并辨别其方向变化来研究这个问题。首先，我们在受试者追踪一个移动的点并关注以视网膜为中心或以空间为中心的光栅时，量化了方向辨别阈值（ODT）。然后，我们在受试者在两个光栅之间分配注意力时测量了 ODT。我们发现，相对于集中注意力条件，分配注意力会使两个目标光栅的 ODT 成比例增加。其次，我们在固定任务期间使用相同的刺激配置和条件。在这里，一个光栅以视网膜和空间为中心，而另一个在空间和视网膜上移动。同样，在分配注意力期间，两个光栅的 ODT 成比例增加。这些增加与在平稳追踪期间测量的增加相似。我们的结果表明，在平稳追踪眼球运动和固定过程中，人类可以按比例在以不同参考系为中心的目标之间分配注意力。
