Attention and perceived stability across eye movements

本研究的目的是探讨注意在维持眼球运动的空间连续性中的作用。眼睛每秒钟移动几次，随着每次眼球运动，整个视觉阵列在视网膜上移动。例如，在驾驶时，我们可能会将视线的方向从后视镜转移到变速杆，导致整个挡风玻璃从较低的视野转移到较高的视野。然而，我们似乎并没有失去整个视觉场景的轨迹，特别是我们似乎没有什么困难，保持我们的注意力集中在重要信息（如迎面而来的交通）将出现的位置。事实上，整个视觉场景在视网膜上的移动对我们主观的空间感和连续性几乎没有影响，尽管当眼睛移动时，视觉皮层中的所有神经元突然开始接收来自空间中一个新位置的信息。必须存在视觉机制，帮助我们在视网膜位置变化时保持相对空间的准确表征。其中一种可能是所谓的眼动重映射：也就是说，一些视觉皮层区域的细胞已经被证明对视觉阵列做出反应，就好像它已经在视网膜上的位置，当即将到来的眼球运动完成时，它将在视网膜上。这个信号的来源似乎至少部分是眼动系统本身。有人认为，通过在眼球运动中提供视觉空间的连续表征，视皮层重新映射是我们主观连续性感觉的基础，尽管对于它对人类观察者的视觉体验有多大贡献尚不清楚。该项目将研究眼球运动的空间稳定性的本质，特别是评估选择性视觉注意是否是该过程的基本组成部分。将解决的具体问题是：眼球运动在多大程度上扰乱了对周边位置的空间注意力？对环境中特定物体的关注在多大程度上决定了它们的空间信息是否会在眼球运动中被保留下来？当物体在我们的视网膜上移动时，我们在多大程度上依赖于稳定的环境信息来跟踪它们？对健康观察者和脑损伤患者的行为研究将用于解决这些问题。答案将揭示潜藏在有意识的视觉体验的连续性的基本机制。

The purpose of this research is to investigate the role of attention in maintaining spatial continuity across eye movements. The eyes move several times each second, and with each eye movement, the entire visual array moves across the retina. When driving, for instance, we may shift our direction of gaze from the rearview mirror to the gear shift, causing the entire windscreen to shift from the lower visual field to the upper visual field. Yet we do not seem to lose track of the visual scene as a whole, and in particular we seem to have little difficulty maintaining the focus of our attention on the locations where important information (such as oncoming traffic) will appear. Indeed, the shift across the retina of the entire visual scene has surprisingly little impact on our subjective sense of space and continuity, despite the fact that when the eyes move, all the neurons in visual cortex suddenly begin receiving information from a new location in space. Visual mechanisms must exist that assist us in maintaining accurate representations of relative space over changes in their retinal positions. One candidate is known as saccadic remapping: namely, cells in some visual cortex regions have been demonstrated to respond to the visual array as though it were already in the retinal locations that it will be in when the impending eye movement is completed. The source of this signal seems to be, at least in part, the eye movement system itself. Saccadic remapping has been suggested to underlie our subjective sense of continuity by providing a continuous representation of visual space over eye movements, though not much is known about how much it actually contributes to visual experience in human observers. This project will investigate the nature of spatial stability over eye movements, specifically assessing whether selective visual attention is a fundamental component of the process. Specific questions that will be addressed are: to what extent do eye movements disrupt spatial attention to peripheral locations? To what extent does attending to specific objects in the environment determine whether their spatial information will be preserved across an eye movement? To what extent do we rely on stable environmental information to keep track of objects when they move on our retina? Behavioural research on healthy observers and patients with brain damage will be used to address these questions. The answers will shed light on the fundamental mechanisms underlying the continuity of conscious visual experience.