Firstly, we need to grasp the fundamental stuff—how information about the outer world is perceived, conveyed, and processed by the senses and the brain; this is often referred to as perception psychology and cognition psychology. On a very basic level, it’s about the brain noting that, for example, something big, black and hairy is crawling across the tiles of the bathroom floor. On a more complex level, it’s about the fascinating phenomenon that people watching exactly the same lecture or event will remember and describe it differently. These issues have been a part of psychology since the field emerged in the nineteenth century. Additionally, naturalists and philosophers have thought and written about it since antiquity.