It has been argued that consciousness might be what differentiates human from machine mentality. What then is consciousness? We discuss consciousness, particularly perception accounts of consciousness. It is argued that perception and consciousness are distinct. Armstrong's (1980) account of consciousness is rejected. It is proposed that perception is a necessary but not sufficient condition for consciousness, and that there is a distinction to be drawn between consciousness and self-consciousness. Consciousness is tightly linked to attention and to certain sorts of knowledge. Implications for machine consciousness and machine attention are discussed.