Bar M
Department of Psychology, Harvard University, Massachusetts General Hospital, MA 02138, USA.
J Cogn Neurosci. 2001 Aug 15;13(6):793-9. doi: 10.1162/08989290152541458.
The nature of visual object representation in the brain is the subject of a prolonged debate. One set of theories asserts that objects are represented by their structural description and the representation is "object-centered." Theories from the other side of the debate suggest that humans store multiple "snapshots" for each object, depicting it as seen under various conditions, and the representation is therefore "viewer-centered." The principal tool that has been used to support and criticize each of these hypotheses is subjects' performance in recognizing objects under novel viewing conditions. For example, if subjects take more time in recognizing an object from an unfamiliar viewpoint, it is common to claim that the representation of that object is viewpoint-dependent and therefore viewer-centered. It is suggested here, however, that performance cost in recognition of objects under novel conditions may be misleading when studying the nature of object representation. Specifically, it is argued that viewpoint-dependent performance is not necessarily an indication of viewer-centered representation. An account for the neural basis of perceptual priming is first provided. In light of this account, it is conceivable that viewpoint dependency reflects the utilization of neural paths with different levels of sensitivity en route to the same representation, rather than the existence of viewpoint-specific representations. New experimental paradigms are required to study the validity of the viewer-centered approach.
大脑中视觉对象表征的本质是一个长期争论的主题。一组理论断言，对象由其结构描述来表征，且这种表征是以“对象为中心”的。争论另一方的理论则表明，人类为每个对象存储多个“快照”，描绘其在各种条件下的样子，因此这种表征是以“观察者为中心”的。用于支持和批评这些假设的主要工具是受试者在新的观察条件下识别对象的表现。例如，如果受试者从一个不熟悉的视角识别对象花费更多时间，通常会认为该对象的表征依赖于视角，因此是以观察者为中心的。然而，这里有人提出，在研究对象表征的本质时，新条件下识别对象的表现成本可能会产生误导。具体而言，有人认为依赖视角的表现不一定表明是以观察者为中心的表征。首先提供了一个关于知觉启动神经基础的解释。鉴于此解释，可以想象视角依赖性反映了在通向相同表征的过程中使用了具有不同敏感程度的神经通路，而不是存在特定于视角的表征。需要新的实验范式来研究以观察者为中心方法的有效性。
