Is Visual Processing in Primates Strictly Hierarchical?

Abstract

Over the past four decades, the dominant view of visual processing in primates is that the complexity of feature analysis increases as information flows from primary visual cortex rostrally through regions of the temporal lobe, into area TE, where whole complex objects are represented. This view is consistent with observations that TE neurons are selective for complex objects such as hands and faces. We test a major prediction: bilateral removal of area TE will damage high-level visual object categorization, such as distinguishing cats from dogs. After removal of TE, this type of categorical classification is only mildly impaired in old-world monkeys. However, when the images are degraded by a small amount of visual noise, the monkeys are virtually unable to correctly classify morphs of cats versus dogs. This raises the possibility that area TE makes it possible to identify partially obscured objects, that is, it is critical for pattern completion.