Top-down modulation of attentional capture in vision: Electrophysiological investigations

想象一下，站在一个繁忙的机场候机楼里，扫描着出发板，寻找你的航班信息。当你关注公告板时，其他感官信息，如行人的视觉和声音，或广播系统的广播，将在很大程度上被忽视。有意识地（或“内源性”）将注意力引导到特定的物体或事件上，使我们能够选择性地忽略与我们当前意图无关的其他感官信息。内源性注意力在日常生活中很明显——它塑造了我们的感知体验，使我们能够处理复杂的多感官世界。没有它，世界将是一片“盛开的、嗡嗡作响的混乱”（威廉·詹姆斯）。然而，内源性注意控制有时会被外部事件打断。即使在浏览离境指示牌时，你的注意力也会被突然的、非常突出的或意想不到的刺激转移，比如闪光或枪声。这些事件被认为是不自觉地或“外源性”地吸引了人们的注意力。内源性控制和外源性注意力捕获之间的区别是我们理解我们如何与外部世界互动的基础。在许多情况下，我们掌控着我们的感官知觉体验的内容，但有时世界上的事件决定了我们能意识到什么。直到最近，似乎很明显，内源性和外源性注意代表了功能和解剖学上不同的注意模式。然而，最近的证据表明，由显著的视觉刺激（比如在许多统一的绿色刺激中，一个独特的红色项目）引起的注意力捕获并不是真正的“外源性”，而是由当前意图控制的。换句话说，外部世界永远不会完全控制我们的感知体验，感知体验也总是由与我们相关的事物决定的。尽管当注意力被有意地集中到其他地方时，显著事件是否被注意到以及在什么条件下被注意到，这个问题对感知和认知理论很重要，但它在很大程度上仍未得到解决。这是因为之前对这一问题的研究主要使用了行为表现指标，这似乎不足以提供明确的答案。在本项目中，我们将使用注意力捕获的电生理标记，这些标记可以在实验任务期间从EEG头皮电极非侵入性地获得。这些标记以毫秒为单位反映了潜在的注意力选择过程的大脑活动，并将用于发现显著的视觉刺激何时以及如何以纯粹的外源性方式捕获观察者的注意力。当参与者执行视觉选择任务时，我们将记录这些标记，在这些任务中，突出的视觉刺激与不太突出的背景刺激的任务相关性被操纵，以找出注意力捕获是否以及如何被故意控制介导。这个项目的目的是为感觉和意图如何相互作用来创造感知体验提供新的见解。从应用的角度来看，研究结果也将产生重要影响，例如在用户界面和复杂控制系统的设计方面。在嘈杂的环境（如机场航站楼）中增加重要视觉信号的可见性的努力可能必须考虑这样一个发现，即这些信号吸引注意力的能力不仅取决于它们自下而上的显著性，还取决于当前的有意背景。

Imagine standing in a busy airport terminal scanning the departure board for information about your flight. While you attend to the board, other sensory information such as the sight and sound of people passing by, or announcements from the PA system, will go largely unnoticed. Directing attention intentionally (or 'endogenously') to specific objects or events enables us to selectively ignore other sensory information that is irrelevant to our current intentions. Endogenous attention is manifest in everyday life - it shapes our perceptual experience and allows us to deal with a complex multisensory world. Without it the world would be a 'blooming, buzzing confusion' (William James). However, endogenous attentional control is sometimes interrupted by external events. Even while scanning the departure board, your attention will be diverted by abrupt, highly salient, or unexpected stimuli, such as a flash of light or a gunshot. Such events are said to capture attention involuntarily, or 'exogenously'. This distinction between the endogenous control and the exogenous capture of attention is fundamental for our understanding of how we interact with the external world. In many cases, we are in charge of the contents of our sensory-perceptual experience, but sometimes events in the world dictate what we become aware of. Until recently, it seemed obvious that endogenous and exogenous attention represent functionally and anatomically distinct modes of attention. However, recent evidence has suggested that attentional capture by salient visual stimuli (such as a unique red item among many uniformly green stimuli) is not really 'exogenous', but is in fact controlled by current intentions. In other words, the external world is never completely in control of our perceptual experience, which is always also determined by what is relevant to us. Although the question whether and under which conditions salient events get noticed when attention is intentionally focused elsewhere is important for theories of perception and cognition, it remains largely unresolved. This is due to the fact that previous research on this issue has used mainly behavioural performance measures, which appear insufficient to provide clear-cut answers. In the present project, we will use electrophysiological markers of attentional capture that can be obtained non-invasively from EEG scalp electrodes during experimental tasks. These markers reflect the activity of brain processes underlying attentional selection processes on a millisecond-by-millisecond basis, and will be used to discover when and how salient visual stimuli will capture observers' attention in a purely exogenous fashion. We will record such markers while participants that perform visual selection tasks where the task relevance of salient visual stimuli that are presented together with less salient background stimuli is manipulated in order to find out whether and how attentional capture is mediated by intentional control. The aim of this project is to provide new insights into how sensation and intention interact to create perceptual experience. Results will also have important implications from an applied perspective, for example with respect to the design of user interfaces and complex control systems. Efforts to increase the noticeability of important visual signals in noisy environments (such as airport terminals) may have to consider the finding that the capacity of such signals to capture attention is not simply determined by their bottom-up saliency, but also by the current intentional context.