Kohlberg, a Harvard University developmental psychologist, studied the field of moral development beginning in the 1970s. Kohlberg believed that moral development and ethical behavior, like cognitive development, depended on the age and problem-solving ability of the individual. His work built upon that of Piaget and other developmental psychologists. According to Kohlberg, children and adults move through three major stages of developing a sense of justice and moral beliefs. These beliefs formed the basis for ethical behaviors. The first stage of moral development is termed preconditional. In this stage, young children learn to behave based on rewards and punishments. Essentially, they learn that by doing what is “good” they will avoid punishments and gain rewards from their parents and other adults. The next stage of moral development was referred to as the conventional level. At this stage, right and wrong is determined by others and is approved behavior. Later in this stage, law and order and fixed rules and regulations are recognized. Moral behavior consists of following the rules of society, authority, or religion. The highest stage of moral development was termed the postconventional or principled level. In this stage, rights are part of a greater social contract, such as the U.S. Constitution. At this level, individuals hold to universal good and ethical principles. Kohlberg believed that individual moral development depended on a person’s cognitive or thinking capacity and exposure to different ideas and human experiences.