The study of intelligence is one of the oldest disciplines. For over two thousand years, philosophers have tried to understand how seeing, learning, remembering, and reasoning could, or should, be done. Humankind gave itself the scientific name homo sapiensman the wisebecause of our mental capacities are so important to our everyday lives and our sense of self. The field of artificial intelligence attempts to understand intelligent entities like our selves as well as build them. There are two things that are needed in order for artificial intelligence to work, intelligence and artifact. Since its invention, the computer has been the popularly acclaimed artifact chosen to be the best chance of demonstrating intelligence. As for the intelligence part, there would have to be some way of showing exactly what it is that actually makes something intelligent. If someone were to say that a given program thought like a human, then there would have to be a way to figure out how humans thought by introspection or through psychological experiments. The field of cognitive science compares computer models from artificial intelligence and experimental techniques from psychology in order to try to build precise and testable theories of the workings of the human mind. Once an understanding can be made on how the human mind works, it becomes possible to express any of these theories as a computer program.