CAREER: Understanding the Relationship of Covert and Overt Attention Using Concurrent EEG and Eye Tracking

在人类中，视觉搜索对于日常目标导向行为至关重要。无论是在开车时扫描道路上的危险，还是在杂货店里寻找一罐汤，人们不断地在复杂的视觉环境中搜索，以定位感兴趣的物体。尽管它很重要，但关于视觉搜索中涉及的大脑过程的许多基本问题仍未得到解答。其中一个问题是，在视觉搜索过程中，大脑是如何控制眼球运动的。人类会产生快速的眼球运动，称为扫视，用来将注意力集中在重要的物体上。这些眼球运动大约每秒发生2-3次，每天大约产生10万次。然而，科学家们才刚刚开始了解这些跳眼运动是如何由不同的大脑区域控制的。目前的项目旨在通过开发一种同时测量眼球运动（通过红外眼球追踪）和神经活动（通过脑电图；EEG）的新技术来弥合这一知识鸿沟。结合这两种类型的数据将使我们能够直接检查大脑中发生在眼球运动产生之前的注意力过程。这个项目将有助于更好地理解眼动背后的基本神经科学。从该项目中获得的知识还将有助于在放射筛查、运输行李安全以及机动车辆交通控制等应用环境中提供视觉搜索的关键见解。这个项目将探索大脑如何控制眼球运动来搜索复杂的图像。先前的研究已经确定了人类视觉注意力的两种机制。首先，眼球跳动被用来快速固定感兴趣的物体。这些弹道眼动每秒发生多次，可以用红外眼动追踪摄像机直接监测。第二，人类也可以在不移动眼睛的情况下偷偷地注视物体。也就是说，人们可以在不直接看物体的情况下“从眼角”监视物体。有趣的是，以前的研究已经开发出直接测量隐蔽注意力的技术，使用脑电图来无创地监测大脑视觉皮层的神经活动。然而，过去这项研究的一个主要缺点是，它使用了禁止眼球运动的搜索任务，因为它们会导致嘈杂的电压波动，使脑电图波形无法解释。因此，人们对大脑在日常视觉搜索中如何使用隐蔽注意力来协调眼球运动知之甚少。目前的项目旨在通过开发一种新技术来测量眼球运动产生之前的大脑活动来解决这个问题。PI将同时测量隐蔽注意力（通过脑电图）和眼球运动（通过红外眼球追踪）的变化。在分析过程中，PI将在眼球运动之前的一段时间内检查脑电图波形，以寻找隐蔽注意选择的标记。具体来说，PI将评估N2pc成分——一种黄金标准的注意力定向脑电图测量方法——是否恰好发生在视觉刺激产生眼球运动之前。此外，该项目将包括一个虚拟研讨会，以培训有前途的年轻研究人员在认知神经科学领域的计算机编程方法。该项目的最终目标是了解在视觉搜索过程中如何使用大脑中的隐蔽注意系统来指导眼球运动，并开发更好的人类视觉注意的认知神经科学模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In humans, visual search is crucial for everyday goal-directed behavior. Whether scanning the road for hazards while driving or looking for a can of soup in a grocery store, people constantly search through complex visual environments to locate objects of interest. Despite its importance, many basic questions about the brain processes involved in visual search remain unanswered. One such question is how eye movements are controlled by the brain during visual search. Humans generate rapid, ballistic eye movements called saccades which are used to focus attention on important objects. These eye movements occur about 2-3 times per second and are generated approximately 100,000 times per day. However, scientists are only beginning to understand how these saccadic eye movements are controlled by different brain areas. The current project aims to bridge this gap in knowledge by developing a new technique to simultaneously measure eye movements (via infrared eye tracking) and neural activity (via electroencephalography; EEG). Combining these two types of data will allow us to directly examine attentional processes in the brain that occur just before eye movements are generated. This project will lead to a better understanding of the basic neuroscience underlying eye movements. The knowledge gained from this project will also help provide key insights about visual search in applied settings such as radiological screening, transportation baggage security, and motor vehicle traffic control.This project will explore how the brain controls eye movements to search through complex images. Prior research has identified two mechanisms of visual attention in humans. First, saccadic eye movements are used to rapidly fixate objects of interest. These ballistic eye movements occur many times per second and can be directly monitored using infrared eye-tracking cameras. Second, humans can also covertly attend objects without moving the eyes. That is, people can monitor an object “out of the corner of their eye” without directly looking at the object. Interestingly, previous research has developed techniques to directly measure covert attention using EEG to noninvasively monitor neural activity from visual cortex in the brain. However, a major shortcoming of this past research is that it used search tasks that prohibited eye movements because they result in noisy voltage fluctuations that make EEG waveforms impossible to interpret. As a result, little is known about how the brain uses covert attention to coordinate eye movements during everyday visual search. The current project aims to resolve this by developing a new technique to measure brain activity that occurs just before eye movement are generated. The PI will measure shifts of covert attention (via EEG) and eye movements (via infrared eye tracking) concurrently. During analysis, the PI will then examine the EEG waveform during the period of time prior to the eye movement for markers of covert attentional selection. Specifically, the PI will assess whether the N2pc component—a gold-standard EEG measurement of attentional orienting—occurs just before eye movements are generated to a visual stimulus. Additionally, this project will involve a virtual workshop to train promising young researchers approaches computer programming in cognitive neuroscience. The ultimate goals of this project are to understand how covert attentional systems in the brain are used to guide eye movements during visual search and to develop better cognitive neuroscience models of visual attention in humans.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.