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Important Psychology Events: 19th Century


The 19th century was when psychology was established as an empirical, accepted science. While measures would change within that 100-year span, the model of research and evaluation would begin to take shape.


  • 1878G. Stanley Hall becomes the first American to earn a Ph.D. in psychology.
  • 1879Wilhelm Wundt establishes the first experimental psychology lab in Leipzig, Germany dedicated to the study of the mind.
  • 1883: G. Stanley Hall opens the first experimental psychology lab in the U.S. at Johns Hopkins University.
  • 1885: Herman Ebbinghaus publishes his seminal "Über das Gedächtnis" ("On Memory") in which he describes learning and memory experiments he conducted on himself.
  • 1886: Sigmund Freud begins offering therapy to patients in Vienna, Austria.
  • 1888James McKeen Cattell becomes the first professor of psychology at the University of Pennsylvania. He would later publish "Mental Tests and Measurements," marking the advent of psychological assessment.
  • 1890William James publishes "Principles of Psychology." Sir Francis Galton establishes correlation techniques to better understand the relationships between variables in intelligence studies.
  • 1892: G. Stanley Hall forms the American Psychological Association(APA), enlisting 26 members in the first meeting.
  • 1896: Lightner Witmer establishes the first psychology clinic in America.
  • 1898Edward Thorndike develops the Law of Effect.

Important Psychology Events: 1900 to 1950


The first half of the 20th century was dominated by two major figures: Sigmund Freud and Carl Jung. It was a time when the foundation of analysis was built, including Freud's examination of psychopathology and Jung's analytic psychology.


  • 1900: Sigmund Freud publishes his landmark book, "Interpretation of Dreams."
  • 1901: The British Psychological Society is established.
  • 1905Mary Whiton Calkins is elected the first woman president of the American Psychological Association. Alfred Binet introduces the intelligence test.
  • 1906Ivan Pavlov publishes his findings on classical conditioningCarl Jung publishes "The Psychology of Dementia Praecox."
  • 1911: Edward Thorndike publishes "Animal Intelligence," which leads to the development of the theory of operant conditioning.
  • 1912Max Wertheimer publishes "Experimental Studies of the Perception of Movement," which leads to the development of Gestalt psychology.
  • 1913: Carl Jung begins to depart from Freudian views and develops his own theories, which he refers to as analytical psychology. John B. Watson publishes "Psychology as the Behaviorist Views" in which he establishes the concept of behaviorism.
  • 1915: Freud publishes work on repression.
  • 1920: Watson and Rosalie Rayner publish research on classical conditioning of fear with their subject, Little Albert.
  • 1932Jean Piaget becomes the foremost cognitive theorist with the publication of his work "The Moral Judgment of the Child."
  • 1942Carl Rogers develops the practice of client-centered therapy, which encourages respect and positive regard for patients.

Important Psychology Events: 1950 to 2000


The latter half of the 20th century was centered around the standardization of the diagnostic criteria of mental illness, hallmarked by the release of the Diagnostic and Statistical Manual of Mental Disorders (DSM) by the American Psychiatric Association. It is the foundational tool still in use today to direct diagnosis and treatment.


  • 1952: The first Diagnostic and Statistical Manual of Mental Disorders is published.
  • 1954Abraham Maslow publishes "Motivation and Personality," describing his theory of a hierarchy of needs. He is one of the founders of humanistic psychology.
  • 1958: Harry Harlow publishes "The Nature of Love," which describes the importance of attachment and love in rhesus monkeys.
  • 1961Albert Bandura conducts his now-famous Bobo doll experimentin which child behavior is described as a construct of observation, imitation, and modeling.
  • 1963: Bandura first describes the concept of observational learning to explain aggression.
  • 1974Stanley Milgram publishes "Obedience to Authority," which describes the findings of his famous obedience experiments.
  • 1980: The DSM-III is published.
  • 1990: Noam Chomsky publishes "On the Nature, Use, and Acquisition of Language."
  • 1991: Steven Pinker publishes an article introducing his theories as to how children acquire language, which he later publishes in the book "The Language Instinct."
  • 1994: The DSM-IV is published.

Important Psychology Events: 21st Century


With the advent of genetic science, psychologists are now grappling with the ways in which physiology and genetics contribute to a person's psychological being.


  • 2002: Steven Pinker publishes "The Blank Slate," arguing against the concept of tabula rasa (the theory that the mind is a blank slate at birth). Avshalom Caspi offers the first evidence that genetics are associated with a child's response to maltreatment.3 Psychologist Daniel Kahneman is awarded the Nobel Memorial Prize in Economics for his research on how people make judgments in the face of uncertainty.
  • 2003: Genetic researchers finish mapping human genes, with the aim of​ isolating the individual chromosomes responsible for physiological and neurological conditions.4
  • 2010: Simon LeVay publishes "Gay, Straight, and the Reason Why," which argues that sexual orientation emerges from prenatal differentiation in the brain.
  • 2013: The DSM-5 is released. Among other changes, the APA removes "gender identity disorder" from the list of mental illnesses and replaces it with "gender dysphoria" to describe a person's discomfort with their assigned gender.
  • 2014: John O'Keefe, May-Britt Moser, and Edvard Moser share the Nobel Prize for their discovery of cells that constitute a positioning system in the brain that is key to memory and navigation.

  • 2020: Darren Stevens creates Constructed Development Theory and unites previously asynchronous theories within psychology by exposing our Self-Awareness. He later releases a book called "Thinking Deliberately" to bring his idea to the masses.

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