Developmental psychology is concerned with understanding both what changes occur with age, and how those changes take place — the process of development. ‘Is there a set pattern? Development psychology’ considers two questions: first, does development take place in stages or is the process more continuous? Second, is development biologically determined by ‘nature’ (genes) or ‘nuture’ (environmental circumstances)? Developmental psychologists propose that there are critical periods in human development during which events must occur, or not occur, for development to proceed normally. Developmental psychologists aim to find ways of ameliorating the effects of negative early experiences, finding remedies for when development is not proceeding normally, and to explore ways of enhancing adjustment throughout the lifespan.