Systems psychology, which is a part of applied psychology, observes human behavior experience in the context of complex systems. It is based on the pioneering theories of Gregory Bateson, Roger Barker and Humberto Maturana. Systems psychology is also referred to as systemic psychology, systems-based psychology and systems behavior.
Various kinds of systems psychology have been cited in scientific literature. In 1970, Kenyon De Greene described applied systems psychology as being closely related to engineering psychology and human factor studies. The principles of systems psychology are cited in the study of cognitive systems theory, family systems, organismic systems and contract-systems psychology.
Ergonomics, also referred to as "engineering psychology" and "human factors," is an example of a form of applied psychology that draws on the observations of systems psychology. Ergonomics is studied in relation to the designs of work systems, health and safety, sports and leisure equipment and work processes. Through the ergonomic observation of the interactions among humans, systems, equipment and machines, designs result that maximize productivity and safety while minimizing discomfort and fatigue. Ergonomists study human capabilities in the context of the demands of work, then contribute to designs and the evaluation of tasks, products, systems and environments in order to make them consistent with peoples' abilities, needs and limitations.
In family systems therapy, also known as family therapy and couples therapy, psychologists, psychotherapists and counselors observe their clients' intimate relationships within families and couples in order to foster development and change. This approach looks at families from the perspective of systems of interaction between the members of the family. In this light, problems are seen as systemic interactions rather than the fault of individual family members.
Systems psychology is an integral part of organizational psychology, which applies psychological theories and and research in resolving workplace problems. The industrial psychologist seeks to make organizations more effective while ensuring that workers are able to enjoy psychologically and physically healthful lives. These psychologists explore areas such as personnel strategies, leadership and motivation, employee recruitment and training as well job and family issues.
The ideas of systems psychology also play a role in perceptual control theory (PCT), a psychological system introduced by William T. Powers. Contrary to most psychological theories of behavior that assume that behavior arises out of perception, PCT holds that the behavior of an organism is a means of controlling and altering its perceptions. In PCT as compared to engineering control theory, the reference variable of negative feedback control loops in a control hierarchy is set by the organism instead of an external agent, changing the controller's setpoint. PCT is also applied in cases involving nonliving autonomic systems.