Attention and perceived stability across eye movements

本研究的目的是探讨注意在维持眼动空间连续性中的作用。眼睛每秒移动几次，随着每一次眼睛移动，整个视觉阵列在视网膜上移动。例如，开车时，我们可能会将视线从后视镜转移到变速器上，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对整个视觉场景的跟踪，特别是我们似乎毫不困难地将注意力集中在重要信息（例如迎面而来的交通）将出现的位置上。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新位置的信息。视觉机制必须存在，帮助我们在视网膜位置变化的情况下保持相对空间的准确表示。其中一个候选者被称为扫视重映射：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的位置，当即将发生的眼球运动完成时，它将在那里。这个信号的来源似乎是，至少部分是，眼球运动系统本身。扫视重映射被认为是通过在眼球运动上提供视觉空间的连续表示来支持我们的主观连续性感觉，尽管对于它实际上对人类观察者的视觉体验有多大贡献还不太清楚。该项目将研究眼动空间稳定性的本质，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。具体的问题，将被解决的是：在多大程度上眼球运动扰乱空间注意周边位置？注意环境中的特定物体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？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。这些答案将揭示有意识视觉体验连续性的基本机制。

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.