The success of outbound training can be attributed to the fact that it uses adult learning principles. Outbound training companies focus onAndragogy (adult learning) which emphasizes the value of the process of learning. It uses approaches to learning that are interactive, problem-based and collaborative rather than moralistic. It also accentuates more equivalence between the trainer and the participants. This science originated in Europe in 1950s and Malcolm Knowles, an American practitioner of adult education, promoted it in the 1970s. Knowles defined andragogy as "the art and science of helping adults learn".