© 2000 by The Society for Integrative and Comparative Biology
Possible Levels of Animal Consciousness with Reference to Grey Parrots (Psittacus erithacus)1
1 Department of Ecology & Evolutionary Biology,
2 
Department of Psychology and Affiliate in Neuroscience, University of Arizona, Tucson, Arizona 85721 and The Media Lab, MIT, Cambridge, Massachusetts 02139
Researchers often study nonhuman abilities by assuming their subjects form representations about perceived stimuli and then process such information; why then would consciousness be required, and, if required, at what level? Arguments about nonhuman consciousness range from claims of levels comparable to humans to refutation of any need to study such phenomena. We suggest that (a) species exhibit different levels attuned to their ecological niches, and (b) animals, within their maximum possible level, exhibit different extents of awareness appropriate to particular situations, much like humans (presumably conscious) who often act without conscious awareness of factors controlling their behavior. We propose that, to engage in complex information processing, animals likely exhibit perceptual consciousness sensu Natsoulas (1978), i.e., are aware of what is being processed. We discuss these issues and provide examples suggesting perceptual consciousness.