Three Levels of Consciousness: A Pattern in Phylogeny and Human Ontogeny

Investigations in the cognitive abilities of different animal species and children at different ages have revealed that consciousness comes in degrees. In this review, I will first address four cognitive abilities that are important to discriminate levels of consciousness: mirror self-recognition, theory of mind, mental time travel, and the capacity to entertain secondary representations. I will then examine putative relations between these abilities and assign them to three levels of consciousness (anoetic, noetic, autonoetic). Finally, I will discuss the implications of differences in consciousness for the understanding of behavioral organization in animals and humans and for animal welfare science. I will argue that, on one hand, implicit behavioral rules may account for results obtained in research on theory of mind and mental time travel abilities in animals and children. On the other hand, secondary representations may be the key to explain behaviors based on semantic memory as well as semantic future planning abilities observed in great apes and young children. These considerations are in accordance with the view that an explicit theory of mind and a continuous self through time are unique to humans.