Vecera S P
Department of Psychology, 11 Seashore Hall E, University of Iowa, Iowa City, IA 52242-1407, USA.
Neuropsychologia. 2002;40(2):187-204. doi: 10.1016/s0028-3932(01)00072-0.
Patients with visual form agnosia exhibit a profound impairment in shape perception (what an object is) coupled with intact visuomotor functions (how to act on an object), demonstrating a dissociation between visual perception and action. How can these patients act on objects that they cannot perceive? Although two explanations of this 'what-how' dissociation have been offered, each explanation has shortcomings. A 'pathway information' account of the 'what-how' dissociation is presented in this paper. This account hypothesizes that 'where' and 'how' tasks require less information than 'what' tasks, thereby allowing 'where/how' to remain relatively spared in the face of neurological damage. Simulations with a neural network model test the predictions of the pathway information account. Following damage to an input layer common to the 'what' and 'where/how' pathways, the model performs object identification more poorly than spatial localization. Thus, the model offers a parsimonious explanation of differential 'what-how' performance in visual form agnosia. The simulation results are discussed in terms of their implications for visual form agnosia and other neuropsychological syndromes.
患有视觉失认症的患者在形状感知（物体是什么）方面存在严重障碍，同时视觉运动功能（如何对物体采取行动）保持完好，这表明视觉感知与行动之间存在分离。这些患者如何对他们无法感知的物体采取行动呢？尽管已经提出了两种对这种“是什么 - 如何做”分离的解释，但每种解释都有缺陷。本文提出了一种关于“是什么 - 如何做”分离的“通路信息”解释。这种解释假设，“在哪里”和“如何做”任务比“是什么”任务需要的信息更少，从而使得在面对神经损伤时，“在哪里/如何做”功能能够相对保留。使用神经网络模型进行的模拟测试了通路信息解释的预测。在“是什么”和“在哪里/如何做”通路共有的输入层受损后，该模型在物体识别方面的表现比空间定位更差。因此，该模型为视觉失认症中不同的“是什么 - 如何做”表现提供了一种简洁的解释。根据模拟结果对视觉失认症和其他神经心理学综合征的影响进行了讨论。
