This chapter discusses the main psychological paradigms used in the past 100 years, psychodynamism, behaviourism and cognitivism based on an information processing paradigm, and later cognitivism based on complex interactive mental processes. It briefly introduces the main concepts of later cognitive psychology: consciousness, sensation, perception, attention, emotion and memory. Each of these concepts will be discussed in detail in later chapters along with their application to tourism. One basic assumption of cognitive psychology is that the brain emerged through evolution and has survival value. However, this means that the brain is not a unified designed organ but has layers of development, one building on the others.