One productive and influential approach to cognition maintains that object categorization and higher-level cognitive processes operate on the output of lower-level perceptual processing. Our perceptual systems provide us with a set of fixed features which are the inputs to higher-level processes. We question this unidirectional approach, arguing that in many situations, categorization and higher-level processes cause lower-level features to be created. Rather than viewing the "vocabulary" of primitives to be fixed by low-level precesses, our view maintains that the vocabulary is dependent on the higher-level processes that use the vocabulary.