The world is all physical reality (Higgs bosons, and so forth), the “environment” is a geographical locality (your city, …), the “Umwelt” is the totality of possible actions of the environment on the sensitive body surface of an agent (you, your dog, …) and the possible actions of the agent on the environment (mechanical, chemical, …), whereas the “innerworld” is what it is for the agent to be, that is awareness. Awareness is pre-personal, proto-conscious, and (perhaps) proto-rational. The various “worlds” described above are on distinct ontological levels. The world, and the environment are studied in the exact sciences, the Umwelt is studied by physiology and ethology. Ethology is like behavioristic psychology, with the difference that it applies to all animals. It skips the innerworld, e.g., it considers speech to be a movement of air molecules.The innerworld can only be known through first person reports, thus is intrinsically subjective. It can only be approached through “experimental phenomenology”, which is based on intersubjectivity among humans. In this setting speech may mean something in addition to the movements of molecules. These views lead to a model of vision as an “optical user interface”. It has consequences for many applications.