Psychophysical evidence and perceptual observations show that object recognition is not hierarchical but is a parallel, simultaneous, egalitarian, non-computational system.

Abstract

Object recognition models have at their core similar essential characteristics: feature extraction and hierarchical convergence leading to a code that is unique to each object and immune to variations in the object appearance. To compare computational, biologically-feasible models to human performance, subjects viewed objects displayed at a wide range of orientations and sizes, and were able to recognize them almost perfectly. These empirical results, together with consideration of thought experiments and analysis of everyday perceptual performance, lead to a conclusion that biologically-plausible object perception models do not even come close to matching our perceptual abilities. We can categorize many thousands of objects, discriminate between enormous numbers of different exemplars within each category, and recognize an object as unique although it may appear in countless variations[-]most of which have never been seen. This seemingly technical, quantitative failure stems from a fundamental property of our perception: the ability to perceive spatial information instantaneously and in parallel, retain details including their relative properties, and yet be able to integrate details into a meaningful percept such as an object. I present an alternative view of object perception whereby objects are represented by responses in primary visual cortex (V1) which is the only cortical area responding to small spatial elements. The rest of the visual cortex is dedicated to scene understanding and interpretation such as constructing 3D percepts from 2D inputs, coding motion, categorization and memories. Since our perception abilities cannot be explained by convergence to "object cells" or by interactions implemented by axonal transmissions, a parallel-to-parallel field-like process is suggested. In this view, spatial information is not modified by multiple neural interactions but is retained by affecting changes in a "neural field" which preserves the identity of individual elements while enabling a new holistic percept when these elements change.