Usage of spatial scales for the categorization of faces, objects, and scenes

The role of spatial scales (or spatial frequencies) in the processing of fa ces, objects, and scenes has recently seen a surge of research activity. In this review, we will critically examine two main theories of scale usage. The fixed theory proposes that spatial scales are used in a fixed, perceptu ally determined order (coarse to fine). The flexible theory suggests instea d that usage of spatial scales is flexible, depending on the requirements o f visual information for the categorization task at hand. The implications of the theories are examined for face, object, and scene categorization, at tention, perception, and representation.