While there is no universal definition of cognition, there are plenty of theories that attempt to describe it. Many of the major themes among these theories are reflections of advances in science, technology, and art that provided us with new metaphors for imagining what is possible. These themes give us different perspectives from which to study cognition and imagine what it is:
Is cognition a product/process/property of our brains? How is it like a computer system? What are its functions as an information processing system based on the operations on abstract symbols?
Is cognition a product/process/property of our relationships? How is it like an ecological system? What are its functions as a network of relationships among people, places, things, and events interacting across time?
Is cognition a product/process/property of our bodies? How is it like a virtual simulation? What are its functions as a synthesis of our physical experiences with the world?
All of these questions and the ways we think about them are transformed if we imagine the themes corresponding to multiple levels of an emergent system. From this frame of reference, we can differentiate among symbolic (conceptual), situated (associative), and embodied (perceptual) as distinct but interdependent levels of cognition.