Abstract
Models designed to explain how shapes are perceived and stored by the nervous system commonly emphasize encoding of contour features, especially orientation, curvature, and linear extent. A number of experiments from my laboratory provide evidence that contours deliver a multitude of location markers, and shapes can be identified when relatively few of the markers are displayed. The emphasis on filtering for orientation and other contour features has directed attention away from full and effective examination of how the location information is registered and used for summarizing shapes. Neural network (connectionist) models try to deal with location information by modifying linkage among neuronal populations through training trials. Connections that are initially diffuse and not useful in achieving recognition get eliminated or changed in strength, resulting in selective response to a given shape. But results from my laboratory, reviewed here, demonstrate that unknown shapes that are displayed only once can be identified using a matching task. These findings show that our visual system can immediately encode shape information with no requirement for training trials. This encoding might be accomplished by neuronal circuits in the retina.
Highlights
Neural network models try to deal with location information by modifying linkage among neuronal populations through training trials
Results from my laboratory, reviewed here, demonstrate that unknown shapes that are displayed only once can be identified using a matching task. These findings show that our visual system can immediately encode shape information with no requirement for training trials
If one assumes the height of the elephant to be 3 meters, at a viewing distance of 10 meters the proximity of adjacent dots would be about 2.5 arc. This would mean that a given receptive field would be activated by a stimulus that had no orientation nor any other contour information that often has been cited as essential for characterizing shapes
Summary
The great obstacle to discovering the shape of the Earth, the continents and the oceans, was not ignorance but the illusion of knowledge. Focusing on the information provided by the black-and-white photograph in the second panel, are the differential shades of gray essential for identifying the animal? The scene can be rendered with fine lines that mark the boundaries of objects, as shown in the third panel of Figure 1. Even the internal contours have been eliminated, leaving only the outer boundaries, yet we can still name the animal figure based on the boundary information. This will come as no surprise to anyone. Shapley and associates [4] have studied the size of these receptive
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