Discontinuity is one dimension of a debate in developmental psychology. Different psychologists argue whether human development occurs in a continuous manner (continuity) or progresses in age-related stages (discontinuity). Discontinuity explains human development as having distinct stages. So, in order to advance an individual must reach a behavioral goal in order to proceed. Developmental theories that support discontinuity are Freud's psychosexual stages, Piaget's stages of cognitive development, and Erikson's theories of development. Continuity could be exemplified by an escalator that moves towards the top floor never stopping while discontinuity is like an elevator that stops at every floor on the way to the top.