Here's Steven Pinker's description of the new model of the brain emerging from the cognitive revolution:
Before the revolution, commentators invoked enormous black boxes such as "the intellect" or "the understanding," and they made sweeping pronouncements about human nature, such as that we are essentially noble or essentially nasty. But we now know that the mind is not a homogeneous orb invested with unitary powers or across-the-board traits. The mind is modular, with many parts cooperating to generate a train of thought or an organized action. It has distinct information-processing systems for filtering out distractions, learning skills, controlling the body, remembering facts, holding information temporarily, and storing and executing rules. Cutting across these data-processing systems are mental faculties (sometimes called multiple intelligences) dedicated to different kinds of content, such as language, number, space, tools, and living things.... Still another layer of information-processing systems can be found in the affect programs, that is, the systems for motivation and emotion.
The upshot is that an urge or habit coming out of one module can be translated into behavior in different ways—or suppressed altogether—by some other module.... More generally, the interplay of mental systems can explain how people can entertain revenge fantasies that they never act on, or can commit adultery only in their hearts. In this way the theory of human nature coming out of the cognitive revolution has more in common with the the Judeo-Christian theory of human nature ... than with behaviorism, social constructivism, and other versions of the Blank Slate. Behavior is not just emitted or elicited, nor does it come directly out of culture or society. It comes from an internal struggle among mental modules with differing agendas and goals.
This modular theory of the mind, when combined with behavioral genetics, challenges Rand's tabula rasa view of the mind, her denial that free will is "saddled" with tendencies, and her ideal of a consciousness "in perfect harmony."