Developmental PsychologyDevelopmental psychology refers to the scientific study of the systematic psychological changes that normally occur in human beings during their growth period, from birth to old age. It originally covered children and infants, but has since expanded to include the entire life span of humanity, including adolescence and adulthood. Developmental psychology covers the extent to which human development occurs through the gradual accumulation of knowledge and the extent to which children born with mental structures from prisoners learn through experience. Different psychological theories and approaches such as behavioral, humanistic, psychoanalytic, biological and cognitive approaches have been developed to explain developmental psychology. This article explains these approaches and theories. Behavioral psychology studies how living organisms develop different behaviors in response to the conditions around them (Lerner, 2002, p. 34). Among the theories that best explain behavioral psychology is Skinner's theory of operant conditioning (Lerner, 2002, p. 53). This theory states that the process of behavioral change does not require repeated efforts but rather requires an immediate reaction to the familiar stimulus. In his experiment on a hungry rat, it was found that several behaviors are learned via reinforcement, which is used to strengthen or discourage a desired behavior of a particular living organism. Lerner (2002) also suggests that humans respond positively to the verbal operant, as they can listen to advice, warnings, and respect rules (p. 59). Because humans have knowledge of what will happen if they choose to behave in a particular way, they can refrain from acting in certain unacceptable… middle of paper… activities such as learning, perceiving, feeling, thinking, and brainpower. Tenenat (2008) states that the brain is the control center for movement, sleep, hunger and virtually every other vital activity necessary for survival. In conclusion, biological psychology is vital during mental illness and for understanding how humans behave, since human behavior is triggered by the mind. Despite its many strengths and supporting facts, biological psychology fails to consider the social and emotional aspect of the person and the things that can affect them outside of their biology. Works Cited Lerner, R 2002, Concepts and Theories of Human Development, Blackwell, Oxford. Piaget, J 1983, Manual of child psychology “Piaget's theory”, Willey, New York.Tenenat, J 2008, The nervous system, consulted on 8 April 2011,