The cortical mechanisms of divided attention in word recognition

 描述(申请人提供)：书面语言是人脑的最高成就：它允许一个人的思想流入另一个人的头脑，尽管他们之间有很长的时间和距离。对于大多数读者来说，这种信息传递是毫不费力的。然而，一次理解多少文本是有限制的；例如，你还不知道下一句话说的是什么。该项目使用行为测试和脑成像相结合的方法来回答以下问题：是否有可能同时识别两个单词？如果没有，哪些内部瓶颈制约了印刷文本的处理？人类观察者会对电脑屏幕两边同时闪现的单词的各个方面做出判断。此外，观察者要么将注意力集中在一个位置，要么将注意力分散在两个位置的单词之间。当他们这样做的时候，他们的大脑活动将被功能磁共振成像记录下来。特别令人感兴趣的是大脑的视觉区域，包括选择性地对单词做出反应的区域。当注意力分散时，一些大脑区域的反应可能不如集中注意力时强烈，这表明这些区域在决定行为准确性方面发挥了作用。此外，通过改变任务的要求，这个项目将揭示视觉文字处理的特定阶段--从提取单个字母的特征到提取语义意义--这些阶段对阅读能力施加了最大的限制。这一结果将加深我们对人脑局限性的理解，为进一步研究应用于学习障碍奠定基础。阅读障碍影响了高达10%的人的阅读，它可能有多种原因，包括单词发音困难(音韵学)。在一些理论中，阅读速度会因为未能按正确的顺序选择小块文本，或者页面上注意力的不正确分配而变慢。因此，通过研究典型读者的视觉注意是如何工作的，这个项目可能会阐明阅读障碍和脑损伤造成的损害的机制。这些知识可以帮助根据每个人面临的挑战设计针对他或她的干预措施。

 DESCRIPTION (provided by applicant): Written language is a crowning achievement of the human brain: it allows the thoughts of one person to flow into the mind of another despite great time and distance between them. For most readers, this information transfer happens effortlessly. Nevertheless, there are limits to how much text can be understood at once; for instance, you do not yet know what the next sentence says. This project uses a combination of behavioral testing and brain imaging to answer the following questions: Is it possible to recognize two words simultaneously? If not, what internal bottlenecks constrain the processing of printed text? Human observers will make judgments about various aspects of words that are flashed simultaneously on both sides of a computer screen. In addition, the observers will either focus attention on one location or divide attention between words at both locations. While they do that, their brain activity will be recorded with functional magnetic resonance imaging. Of particular interest are the visual areas of the brain, including one that responds selectively to words. Some brain areas may respond less strongly when attention is divided than focused, indicating that those areas play a role in determining behavioral accuracy. Furthermore, by varying the demands of the task, this project will uncover the particular stages of visual word processing-from extracting the features of individual letters to retrieving the semantic meaning-that impose the greatest limits on reading ability. The results will enhance our understanding of the limitations of the human brain, setting the stage for further research applied to learning disabilities. Dyslexia impairs reading for up to 10 percent of the population, and it may have multiple causes including difficulties with word sounds (phonology). In some theories, reading is slowed by failures to select small chunks of text in the correct order, or by improper division of attention across the page. Therefore, by studying how visual attention works in typical readers, this project may elucidate the mechanisms of dyslexia and impairments caused by brain damage. That knowledge can help design interventions targeted to each individual according to the challenges he or she faces.