Etymology and History
- The word 'psychology' derives from the Greek word 'psyche,' meaning spirit or soul.
- The term 'psychology' comes from the Greek word '-λογία,' which means study or research.
- The word 'psychology' was first used in the Renaissance.
- In its Latin form 'psychiologia,' it was first employed by the Croatian humanist Marko Marulić.
- The earliest known reference to the word 'psychology' in English was by Steven Blankaart in 1694.
- Ancient civilizations like Egypt, Greece, China, India, and Persia studied psychology.
- Greek philosophers, including Thales, Plato, and Aristotle, addressed the workings of the mind.
- Hippocrates theorized that mental disorders had physical causes.
- Plato suggested that the brain is where mental processes take place.
- Aristotle suggested that the heart is the center of mental processes.

Subject Matter and Practitioners
- Psychology studies the mind and behavior of humans and nonhumans.
- It includes conscious and unconscious phenomena.
- Mental processes such as thoughts, feelings, and motives are part of psychology.
- Psychology is an academic discipline that crosses boundaries between natural and social sciences.
- Biological psychologists study the emergent properties of brains and link psychology to neuroscience.
- Psychologists are professional practitioners or researchers in the field.
- Some psychologists are classified as behavioral or cognitive scientists.
- Psychologists study the role of mental functions in behavior.
- Others explore physiological and neurobiological processes underlying cognitive functions and behaviors.
- Psychologists conduct research on perception, cognition, emotion, intelligence, and personality.

Applications and Development
- Psychology is applied to the assessment and treatment of mental health problems.
- It is also used to understand and solve problems in various spheres of human activity.
- Many psychologists practice psychotherapy in clinical, counseling, or school settings.
- Some psychologists conduct scientific research on mental processes and behavior.
- Psychologists work in academic, industrial, organizational, and other settings.
- Wilhelm Wundt established the first psychological laboratory in Leipzig, Germany.
- Gustav Fechner conducted psychophysics research and developed the Weber-Fechner law.
- Hermann von Helmholtz conducted research on sensory perception.
- Paul Flechsig and Emil Kraepelin established a psychology-related laboratory in Leipzig.
- Hermann Ebbinghaus pioneered the experimental study of memory.

International Spread and Consolidation
- Psychologists in Germany, Denmark, Austria, England, and the United States established laboratories.
- G. Stanley Hall founded an influential psychology laboratory at Johns Hopkins University.
- Yujiro Motora brought experimental psychology to the Imperial University of Tokyo.
- Narendra Nath Sen Gupta founded a psychology department and laboratory at the University of Calcutta.
- Psychology programs and research spread to various countries, including Argentina and Russia.
- La Société de Psychologie Physiologique was one of the earliest psychology societies.
- The International Congress of Psychology began in 1889 and continued with international participation.
- The American Psychological Association (APA) was founded in 1892.
- Psychology gained status in the U.S. during World War I through mental testing.
- The Rockefeller family and foundations provided funding for behavioral research and mental hygiene.

Influence and Regulation
- Rockefeller foundations supported research on sexuality through Alfred Kinsey.
- The eugenics movement influenced American psychology in the early 20th century.
- Psychology faced antagonism in the UK from scientific and medical establishments.
- The U.S. military and intelligence agencies funded psychology research during World War II and the Cold War.
- Propaganda research became significant during the war, with social psychologists involved in shaping policies.
- Psychologists played significant roles in managing the domestic economy.
- The Berlin Psychoanalytic Institute was renamed the Göring Institute under Nazi rule.
- Freudian psychoanalysts were expelled and persecuted due to anti-Jewish policies.
- The Göring Institute aimed to create a New German Psychotherapy to align Germans with the goals of the Reich.
- Alexander Mitscherlich founded the applied psychoanalysis journal 'Psyche' and established the first clinical psychosomatic medicine division.
- Psychology was integrated into the required studies of medical students.
- Chinese psychology initially modeled itself on U.S. psychology, with a focus on education and language learning.
- Governments in some places legally regulate who can provide psychological services.
- The APA defines a psychologist as someone with a doctoral degree in psychology.