Categorization and Expertise in Human Visual Cognition

9615819 TARR这项研究将调查人类观察者在不同分类和专门知识水平上使用的视觉识别机制，特别是参考人脸和非人脸物体之间的差异。早期声称人脸识别机制的研究包括一些实验上的混淆。解决这些问题首先需要使用计算机图形学来创建精心控制的三维对象，以便在心理物理、神经心理学和功能神经成像实验中进行演示。这些对象将包括一组非Face控制对象，它们将结合Face的几个属性(例如部件的固定配置和整个类的同质性)，但不包括它们的表面特征。第一组心理物理实验将使用这些新的刺激以及熟悉的对象类别，以评估文献中描述的几种“特定于面部”的行为效果中的哪一种可以获得：a)个体，而不是对相同对象的更明确的判断；b)专家，而不是新手参与者。新的专门知识培训程序将提供操纵参与者对新对象类别的经验的方法，以及更好地理解在获得专门知识期间可能发生的识别机制的重组。第二组实验将测试在同一对象类别的神经心理学实验中，传统上被归类为面孔特定障碍的脑病患者，以测试面孔识别缺陷是否可以更好地描述为样本水平处理机制的损害。对这些患者的测试将以更接近正常参与者测试标准的方式进行，方法是改进对物体呈现和反应测量的控制，特别是使用反应时和信号检测测量S。其他实验将使用为研究正常人创造专业知识而开发的方法，以探索认知缺陷患者视觉系统的可塑性。第三组实验将使用功能磁共振成像(FMRI)研究样本与类别水平视觉判断的神经基础。虽然将人脸加工与非人脸物体的样本级加工进行比较的重要性已经得到承认，但很少有研究比较同一物体不同抽象水平上的识别判断，特别是在参与者从新手开始，然后获得对物体类别的经验的条件下。纵向功能磁共振研究将在多个分类水平上评估专业知识获取背后的神经变化。总体而言，这些实验应该能揭示视觉系统中的人脸特异性问题，提供关于分类水平和对象识别专业知识的作用的数据，探索视觉形式识别缺陷患者的康复可能性，并扩大我们对人类视觉系统可塑性的理解。***

9615819 TARR This research will investigate visual recognition mechanisms employed by human observers across different levels of categorization and expertise, with particular reference to the difference between faces and non-face objects. Earlier studies making claims for face-specific recognition mechanisms include a number of experimental confounds. Addressing these concerns will first require the use of computer graphics to create carefully controlled three-dimensional objects for presentation in psychophysical, neuropsychological, and functional neuroimaging experiments. These objects will include a set of non-face control objects that will combine several properties of faces (such as a fixed configuration of parts and homogeneity across the class) but none of their superficial characteristics. A first set of psychophysical experiments will use these novel stimuli, as well as familiar classes of objects, to assess which of the several "face-specific" behavioral effects described in the literature can be obtained for a) individual as opposed to more categorical judgments for the same objects and, b) with experts as opposed to novice participants. New expertise training procedures will provide methods for manipulating participants' experience with the novel object class as well as a better understanding of the reorganization of recognition mechanisms that may occur during expertise acquisition. A second set of experiments will test brain-lesioned patients traditionally classified as having a face-specific disorder in neuropsychological experiments with the same object class to test whether face-recognition deficits may be better described as an impairment of exemplar-level processing mechanisms. Testing of these patients will be performed in a manner closer to what is standard in the testing of normal participants, by improving the control of object presentation and of response measurements, in particular using reaction times and signal detection measure s. Other experiments will use methods developed for studying the creation of expertise in normals to explore the plasticity of the visual system of patients with recognition deficits. A third set of experiments will study the neural substrate of exemplar vs. categorical level visual judgments using functional magnetic resonance imaging (fMRI). While the importance of comparing face processing to exemplar-level processing of non-face objects has been acknowledged, few studies have compared recognition judgments at different levels of abstraction for the same objects, in particular, under conditions where participants begin as novices and then gain experience with an object class. Longitudinal fMRI studies will assess the neural changes underlying expertise acquisition at multiple levels of categorization. Overall, these experiments should shed some light on the issue of face-specificity in the visual system, provide data about the role of categorization level and expertise for object recognition, explore rehabilitation possibilities for patients with visual form recognition deficits, and extend our understanding of the plasticity of the human visual system. ***