Psychology

For other uses, see Psychology (disambiguation).

Psychology is the scientific study of mind and behavior.^[1][2] Its subject matter includes the behavior of humans and nonhumans, both conscious and unconscious phenomena, and mental processes such as thoughts, feelings, and motives. Psychology is an academic discipline of immense scope, crossing the boundaries between the natural and social sciences. Biological psychologists seek an understanding of the emergent properties of brains, linking the discipline to neuroscience. As social scientists, psychologists aim to understand the behavior of individuals and groups.^[3][4]

A professional practitioner or researcher involved in the discipline is called a psychologist. Some psychologists can also be classified as behavioral or cognitive scientists. Some psychologists attempt to understand the role of mental functions in individual and social behavior. Others explore the physiological and neurobiological processes that underlie cognitive functions and behaviors.

Psychologists are involved in research on perception, cognition, attention, emotion, intelligence, subjective experiences, motivation, brain functioning, and personality. Psychologists' interests extend to interpersonal relationships, psychological resilience, family resilience, and other areas within social psychology. They also consider the unconscious mind.^[5] Research psychologists employ empirical methods to infer causal and correlational relationships between psychosocial variables. Some, but not all, clinical and counseling psychologists rely on symbolic interpretation.

While psychological knowledge is often applied to the assessment and treatment of mental health problems, it is also directed towards understanding and solving problems in several spheres of human activity. By many accounts, psychology ultimately aims to benefit society.^[6][7][8] Many psychologists are involved in some kind of therapeutic role, practicing psychotherapy in clinical, counseling, or school settings. Other psychologists conduct scientific research on a wide range of topics related to mental processes and behavior. Typically the latter group of psychologists work in academic settings (e.g., universities, medical schools, or hospitals). Another group of psychologists is employed in industrial and organizational settings.^[9] Yet others are involved in work on human development, aging, sports, health, forensic science, education, and the media.

The word psychology derives from the Greek word psyche, for spirit or soul. The latter part of the word psychology derives from -λογία -logia, which means "study" or "research".^[10] The word psychology was first used in the Renaissance.^[11] In its Latin form psychiologia, it was first employed by the Croatian humanist and Latinist Marko Marulić in his book Psichiologia de ratione animae humanae (Psychology, on the Nature of the Human Soul) in the decade 1510-1520^[11][12] The earliest known reference to the word psychology in English was by Steven Blankaart in 1694 in The Physical Dictionary. The dictionary refers to "Anatomy, which treats the Body, and Psychology, which treats of the Soul."^[13]

Ψ (psi), the first letter of the Greek word psyche from which the term psychology is derived, is commonly associated with the field of psychology.

In 1890, William James defined psychology as "the science of mental life, both of its phenomena and their conditions."^[14] This definition enjoyed widespread currency for decades. However, this meaning was contested, notably by radical behaviorists such as John B. Watson, who in 1913 asserted that the discipline is a natural science, the theoretical goal of which "is the prediction and control of behavior."^[15] Since James defined "psychology", the term more strongly implicates scientific experimentation.^[16][15] Folk psychology is the understanding of the mental states and behaviors of people held by ordinary people, as contrasted with psychology professionals' understanding.^[17]

Main article: History of psychology

For a chronological guide, see Timeline of psychology.

The ancient civilizations of Egypt, Greece, China, India, and Persia all engaged in the philosophical study of psychology. In Ancient Egypt the Ebers Papyrus mentioned depression and thought disorders.^[18] Historians note that Greek philosophers, including Thales, Plato, and Aristotle (especially in his De Anima treatise),^[19] addressed the workings of the mind.^[20] As early as the 4th century BC, the Greek physician Hippocrates theorized that mental disorders had physical rather than supernatural causes.^[21] In 387 BCE, Plato suggested that the brain is where mental processes take place, and in 335 BCE Aristotle suggested that it was the heart.^[22]

In China, psychological understanding grew from the philosophical works of Laozi and Confucius, and later from the doctrines of Buddhism.^[23] This body of knowledge involves insights drawn from introspection and observation, as well as techniques for focused thinking and acting. It frames the universe in term of a division of physical reality and mental reality as well as the interaction between the physical and the mental.^{[citation needed]} Chinese philosophy also emphasized purifying the mind in order to increase virtue and power. An ancient text known as The Yellow Emperor's Classic of Internal Medicine identifies the brain as the nexus of wisdom and sensation, includes theories of personality based on yin–yang balance, and analyzes mental disorder in terms of physiological and social disequilibria. Chinese scholarship that focused on the brain advanced during the Qing dynasty with the work of Western-educated Fang Yizhi (1611–1671), Liu Zhi (1660–1730), and Wang Qingren (1768–1831). 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.^[24]

Influenced by Hinduism, Indian philosophy explored distinctions in types of awareness. A central idea of the Upanishads