This may be relevant, since we are dealing with things that make us crazy. I went a little before and after the 20s to give an idea of where the science is at that time.
1900 – Sigmund Freud published ‘Interpretation of Dreams’ marking the beginning of Psychoanalytic Thought.
1903 – John B. Watson graduated from the University of Chicago. His dissertation on rat behavior has been described as a “classic of developmental psychobiology” by historian of psychology, Donald Dewsbury.
1904 – Charles Spearman published the article General Intelligence in the American Journal of Psychology, introducing the g factor theory of intelligence.
1905 – Alfred Binet and Theodore Simon created the Binet-Simon scale to identify students needing extra help, marking the start for standardized psychological testing.
1906 – The Journal of Abnormal Psychology founded by Morton Prince for which Boris Sidis was an associate editor and significant contributor.
1909 – Sigmund Freud lectured at Clark University.
1910 – Boris Sidis opens the Sidis Psychotherapeutic Institute (a private hospital) at Maplewood Farms in Portsmouth, NH for the treatment of nervous patients using the latest scientific methods.
1911 – Alfred Adler left Freud’s Psychoanalytic Group to form his own school of thought, accusing Freud of overemphasizing sexuality and basing his theory on his own childhood.
1912 – Max Wertheimer published Experimental Studies of the Perception of Movement, considered the founding article of Gestalt psychology
1913 – Carl Jung departed from Freudian views and developed his own theories citing Freud’s inability to acknowledge religion and spirituality. His new school of thought became known as Analytical Psychology.
1913 – Jacob L. Moreno applied Group Psychotherapy methods in Vienna. His new methods, which emphasised spontaneity and interaction, later became known as Psychodrama and Sociometry.
1913 – John B. Watson published Psychology as the Behaviorist Views It, sometimes known as “The Behaviorist Manifesto”.
1914 – Boris Sidis publishes The Foundations of Normal and Abnormal Psychology where he provides the scientific foundation for the field of psychology, and details his theory of the moment-consciousness.
1920 – John B. Watson and Rosalie Rayner conducted the Little Albert experiment, using classical conditioning to make a young boy afraid of white rats.
1921 – Jacob L. Moreno conducted the first large scale public Psychodrama session at the Komoedienhaus, Vienna. He moves to New York in 1925.
1922 – Boris Sidis publishes Nervous Ills: Their Cause and a Cure, a popularization of his work concerning the subconscious and the treatment of psychopathic disease.
1927 – Ivan Pavlov publishes book on Classical Conditioning.
1928 – Jean Piaget’s book Judgement and Reasoning in the Child is published.
1929 – Drake Bell publishes The life and times of Tim Blake before he is shot.
1934 – Lev Vygotsky’s Thought and Language (a.k.a. Thinking and Speech) is first published (in Russian)
1935 – John Ridley Stroop developed a color-word task to demonstrate the interference of attention, the Stroop effect
1938 – B.F. Skinner published his first major work, The Behavior of Organisms: An Experimental Analysis, introducing behavior analysis.
1939 – Alan Hodgkin and Andrew Huxley published a classic report in the journal Nature of the first recording of an action potential.