Wang Qingren emphasized the importance of the brain as the center of the nervous system, linked mental disorder with brain diseases, investigated the causes of dreams and insomnia, and advanced a theory of hemispheric lateralization in brain function.
Distinctions in types of awareness appear in the ancient thought of India, influenced by Hinduism.
It frames the universe as a division of, and interaction between, physical reality and mental reality, with an emphasis on purifying the mind in order to increase virtue and power.
Many do scientific research on a wide range of topics related to mental processes and behavior, and typically work in university psychology departments or teach in other academic settings (e.g., medical schools, hospitals).
Some are employed in industrial and organizational settings, or in other areas The earliest known reference to the word psychology in English was by Steven Blankaart in 1694 in The Physical Dictionary which refers to "Anatomy, which treats the Body, and Psychology, which treats of the Soul." In 1890, William James defined psychology as "the science of mental life, both of its phenomena and their conditions".
Watson, who in his 1913 manifesto defined the discipline of psychology as the acquisition of information useful to the control of behavior.
Also since James defined it, the term more strongly connotes techniques of scientific experimentation.
In Germany, Gottfried Wilhelm Leibniz (1646–1716) applied his principles of calculus to the mind, arguing that mental activity took place on an indivisible continuum—most notably, that among an infinity of human perceptions and desires, the difference between conscious and unconscious awareness is only a matter of degree.