Knowing the World

The world we live in is packed with an enormous variety of objects, people, and events, differing in size, shape, and colour -- a quick look around any room reveals furniture, books, pictures, and countless other things, and moving to a different room or stepping outside reveals still more. We usually come to know all of this without any deliberate effort, because our sense organs -- eyes, ears, nose, tongue, and skin -- gather information not just from the external world but from our own body as well, and this gathered information forms the foundation of everything we know. For this information to actually be useful, though, the objects and their qualities (size, shape, colour, and so on) first have to draw our attention; the registered information is then carried to the brain, which constructs meaning out of it. Our knowledge of the world therefore rests on three basic, closely interrelated processes: sensation (the initial registering of a stimulus), attention (the selecting of certain stimuli for further processing), and perception (the interpreting and meaning …