Chapter overview Section 1 of this chapter focuses on how human individuals deal with environmental information and settings. We follow the history of psychology, which began investigating how the human individual perceives the environment through the senses. We progress from perceiving to storing and processing environmental information. We learn how theories in these fields are tied to fundamental assumptions about how and why environmental information is acquired. We introduce Egon Brunswik’s theory of probabilistic functionalism, which is a cornerstone for the epistemology underlying this book. This theory provides basic assumptions about human–environment interactions, which are included in the HES framework (see Chapters 3, 16, and 17). Another cornerstone is Kurt Lewin’s field theory. On our journey through psychology we will repeatedly pose questions on the nature–nurture interplay (i.e. what is innate vs. what is learned), the realist–idealist dichotomy (i.e. what is real/true and what is subjectively, individually constructed), or how the human mind and behavior are adapted to the environmental setting. We present the geopsychology, ecological theory, and ecopsychology approaches, which make different assumptions about the relationship between humans and their environment. We discuss the transactionalist concept, which is essential for the HES framework. Section 2 introduces Jean Piaget’s theory of cognitive development, in particular the concept of genetic epistemology, which relates ontogeny (i.e. the cognitive development of the individual) with phylogeny (i.e. the cognitive development of the human species).