Jean Pierre Étienne Vaucher

Voluntarism, sometimes referred to as voluntary action, is the principle that individuals are free to choose goals and how to achieve them within the bounds of certain societal and cultural constraints, as opposed to actions that are coerced or predetermined.

Mandayam Osuri Parthasarathy Iyengar

Applied psychology is the use of psychological methods and findings of scientific psychology to solve practical problems of human and animal behavior and experience. This could be described as human factor psychology or as applied cognitive psychology.

Physiological psychology is a subdivision of behavioral neuroscience (biological psychology) that studies the neural mechanisms of perception and behavior through direct manipulation of the brains of nonhuman animal subjects in controlled experiments.

Military psychology is a specialization within psychology that applies psychological science to promote the readiness of military members, organizations, and operations. Clinical providers in military psychology are often focused on the treatment of stress, fatigue, and other personal readiness issues.

Behavioral neuroscience also known as biological psychology, biopsychology, or psychobiology is the application of the principles of biology to the study of physiological, genetic, and developmental mechanisms of behavior in humans and non-human animals.

Health psychology examines how biological, social and psychological factors influence health and illness. Health psychologists use psychological science to promote health, prevent illness and improve health care systems.

Psychophysiology is different from physiological psychology in that psychophysiology looks at the way psychological activities produce physiological responses, while physiological psychology looks at the physiological mechanisms which lead to psychological activity. Psychophysiology is a specialized field.