Cognitive psychology is a study of the internal mental processes a person has. It has to do with how people mentally represent information processing. Experiments in this field have to do with stimulus and response. Jean Piaget is one of the most famous cognitive psychologists. His work has to do with developmental stages in children. Unlike some other theories, cognitive psychology accepts the scientific method and recognizes internal mental states such as motivation, desire, and belief.
Cognitive psychology is the study of mental processes. Cognitive processes happen in the mind/brain. They include perception, memory, attention, language, problem solving decision-making, thinking and so on.