CAREER: The Time Course of Bottom-up and Top-down Integration in Language Understanding

环境改变了我们理解景象和声音的方式。一种介于黄色和绿色之间的颜色，用在香蕉上看起来更黄，但用在酸橙上看起来更绿。在“p”和“b”中间的声学模式被解释为“p”跟着“sto-”，但“b”跟着“sta-”。但是，环境真的会改变视觉和声音的感知，还是只会改变它们的解释？长期以来，认知科学家一直在争论“自下而上”的输入信号（如语音）何时以及如何与“自上而下”的信息（语境或记忆中的知识）相结合。是早期的感知过程保护了“正确的”、与上下文无关的信号记录，还是感知过程立即混合了自下而上和自上而下的信息？一种观点认为，准确的感知需要自下而上和自上而下信息的早期分离和后期整合。另一种选择是，通过允许上下文立即指导处理，将自底向上和自顶向下信息的早期混合将使系统更有效。在语言理解的研究中，这个时间问题尚未解决，因为从两种即时处理的测量中得到的证据相互矛盾。追踪人们在口头指示下对物体的眼球运动的研究支持即时整合：有用的信息似乎一得到就会被使用。使用ERPs（事件相关电位，通过头皮电极测量皮层活动）的研究表明，整合延迟：早期大脑反应似乎只受到自下而上信息的影响。这两种测量的结果很难比较，因为它们依赖于非常不同的实验设计。在拟议的研究中，研究者将使用实验设计来研究人类句子处理中自上而下整合的时间，该实验设计允许同时比较眼动追踪和erp，目的是确定自上而下的上下文何时以及如何与自下而上的信号信息整合。所提出的工作对语言技术的设计具有重要的意义。与计算机系统相比，人类可以有效地利用自上而下的环境，并迅速学会适应新的环境。使计算机系统像人类一样具有适应性的一个障碍是，我们并不完全了解人类如何平衡自下而上的信号和自上而下的环境。这项研究对理解和治疗语言障碍也有意义。例如，了解正常感知者如何平衡和整合信号和环境可能有助于识别导致对环境异常依赖的微妙的自下而上的损伤。研究者致力于将本CAREER项目的研究和培训活动结合起来，并将积极地让本科生和研究生参与研究。研究者还将开发课程，通过提供认知理论和时间课程方法的实践培训，为学生的独立研究做准备。

Context changes the way we interpret sights and sounds. A shade of color halfway between yellow and green looks more yellow when applied to a picture of a banana, but more green when applied to a lime. An acoustic pattern halfway between "p" and "b" is interpreted as "p" following "sto-" but as "b" following "sta-". But does context actually alter perception of sights and sounds, or only their interpretation? Cognitive scientists have long debated when and how "bottom-up" input signals (such as speech) are integrated with "top-down" information (context, or knowledge in memory). Do early perceptual processes protect a "correct," context-independent record of signals, or do perceptual processes immediately mix bottom-up and top-down information? One view is that accurate perception requires early separation of bottom-up and top-down information and late integration. An alternative is that early mixing of bottom-up and top-down information would make systems more efficient, by allowing context to immediately guide processing. In studies of language comprehension, this timing question is unsettled because of conflicting evidence from two measures of moment-to-moment processing. Studies tracking people's eye movements on objects upon verbal instructions support immediate integration: helpful information appears to be used as soon as it is available. Studies using ERPs (event related potentials, which measure cortical activity via scalp electrodes) suggest delayed integration: early brain responses appear to be affected only by bottom-up information. Results from the two measures have been difficult to compare because they have relied on very different experimental designs. In the proposed research the investigator will study the timing of top-down integration in human sentence processing using experimental designs that allow simultaneous comparisons of eyetracking and ERPs, with the goal of determining when and how top-down context is integrated with bottom-up signal information. The proposed work has important implications for the design of language technology. In contrast to computer systems, humans efficiently exploit top-down context, and quickly learn to adapt to new contexts. An obstacle to making computer systems as adaptable as humans is that we do not fully understand how humans balance bottom-up signals and top-down context. The proposed research also has implications for understanding and treating language impairments. For example, understanding how normal perceivers balance and integrate signal and context may help identify subtle bottom-up impairments that lead to unusual reliance on context. The investigator is committed to integrating research and training activities in this CAREER project, and will actively involve undergraduate and graduate students in the research. The investigator will also develop courses designed to prepare students for independent research by providing hands-on training in cognitive theories and time course methodologies.