Quite simply, cognition refers to thinking. There are the obvious applications of conscious reasoning—doing taxes, playing chess, deconstructing Macbeth—but thought takes many subtler forms, such as interpreting sensory input, guiding physical actions, and empathizing with others. The old metaphor for human cognition was the computer—a logical information-processing machine. You can’t spell cognition without the “cog.” Yet while some of our thoughts may be binary, there's a lot more to our “wetware” than 0's and 1's. Research on cognition focuses not just on thinking, but also on attention, the creation and storage of memories, knowledge acquisition and retention, language learning, and logical reasoning. As people gain new experiences, their cognition can change in subtle but powerful ways as a result.