A developmental psychologist investigates the emotional, mental, physical, and social development of individuals that takes place throughout life. Their focus used to be on childhood and adolescence, as one may study children to analyze learning processes, language development, and parents' influence on behavior, or study infants for patterns of social, motor, and sensory development. However, as life expectancy increases, they are becoming increasingly interested in aging, especially in researching and developing ways to help elderly people stay as independent as possible. One may administer tests to gauge patterns of development and decline, conduct animal experiments, or formulate theories for use in such fields as juvenile delinquency, education/guidance of children, parent education, and welfare of aged. May specialize in study and treatment of children and be designated a Child Psychologist. To be a developmental or child psychologist requires a doctorate degree.