William James was an American psychologist and philosopher. Widely regarded as the father of American psychology and one of the most influential American philosophers, James was the first educator in the United States to offer a course in psychology. He is also credited with co-founding a psychological school of thought called functional psychology and establishing a philosophical school called pragmatism.
Lev Vygotsky was a Soviet psychologist best remembered for his groundbreaking work on developmental psychology in children. He is also remembered for his work on the relationship between thought and language, which remains influential to this day. A man with various interests, Vygotsky's work covered topics like the philosophy of science and the psychology of art.
Alfred Adler was an Austrian psychotherapist and medical doctor. He is credited with founding the school of individual psychology. He was also one of the founders of the psychoanalytic movement along with Sigmund Freud and Freud's colleagues. In 2002, a survey conducted by Review of General Psychology named Adler among the 20th century's most eminent psychologists.
Wilhelm Wundt was a German physiologist, professor, and philosopher. He is often counted among the founders of modern psychology and is widely considered the father of experimental psychology. He is also credited with founding the first laboratory for psychological research, which he founded at the University of Leipzig in 1879.
A staunch advocate of progressive education and liberalism, the American philosopher and psychologist was the founder of the University of Chicago Laboratory Schools. John Dewey’s famous writings included The Reflex Arc Concept in Psychology and Human Nature and Conduct. According to him, passion for knowledge and intellectual curiosity were central to a teacher. He called himself a democratic socialist.
Melanie Klein was an Austrian-British author and psychoanalyst. A key figure in the development of object relations theory, she is best known for her work in child analysis. She began her studies by observing her own children’s behavior while they were growing up. As a woman in a field dominated by men, she was also a feminist icon.
11 Fritz Perls
Fritz Perls initially fought in World War I, following which he treated brain injuries of soldiers. He was later drawn to Freudian psychoanalysis. During World War II, he was the psychiatrist for the South African military. His Gestalt therapy, which he co-created with his wife, Laura, redefined psychology.
12 Elton Mayo
Elton Mayo was an Australian-born industrial researcher, psychologist, and organizational theorist. As a psychologist, Mayo played an important role during World War I, helping soldiers returning from the war recover from the stresses. He also conducted psycho-pathological tests and is credited with pioneering the psychoanalytic treatment of shell-shock. Elton Mayo's works also laid the basis for the human relations movement.
French social psychologist Gustave Le Bon is best remembered for his research on crowd psychology. In his iconic work La psychologie des foules, or The Crowd, he stated that people are driven by their emotions and not by their intellect when they act as part of a crowd.
Russian-born German author Lou Andreas-Salomé apparently rejected renowned philosopher Friedrich Nietzsche’s marriage proposal and then married a professor instead. A skilled psychoanalyst, she was also close to Rainer Maria Rilke and Sigmund Freud. She was one of the first to offer a psychoanalytic perspective to female sexuality.
Born in Prussia, Magnus Hirschfeld had initially studied languages and had then earned a medical degree. He grew up to be a prominent sexologist and gay rights activist who referred to the LGBT community as the “third sex.” His one-of-a-kind sexology institute was later destroyed by the Nazis.
Especially remembered for his pioneering work on rote learning and memory, German psychologist Hermann Ebbinghaus became interested in the subject after reading Gustav Fechner's Elements of Psychophysics. Eventually, he developed the experimental methods for measuring memory, using 2,300 three-letter nonsense syllables that he devised. Later, he also discovered the forgetting curve and the spacing effect and described the learning curve.
19 Otto Rank
Otto Rank was an Austrian psychoanalyst and philosopher. A close colleague of Sigmund Freud, Rank was also the managing director of Freud's publishing house. Rank was a prolific writer and wrote extensively on psychoanalytic themes. He was the first person who viewed therapy as a learning and unlearning experience focusing on feelings. Psychologist Rollo May was deeply influenced by Rank.
The son of a musician, Emil Kraepelin, remembered as the founder of psychiatry, was the first to differentiate between dementia praecox, now known as schizophrenia, and manic-depressive psychosis. His classification of mental illnesses influenced much of the research on the subject in the 20th century.
21 Lewis Terman
Austrian thinker Otto Weininger, whose main areas of interests included philosophy of religion, logic, gender and psychology, lived in the Austro-Hungarian Empire. His book Geschlecht und Charakter (Sex and Character), which gained popularity following his suicide by gunshot, became a sourcebook for anti-Semitic propagandists. Some of his writings were used by Nazi propaganda.
24 Wilfred Bion
Born in British India, Wilfred Bion grew up to be a prominent psychoanalyst. He had fought during World War I. He is best remembered for his work on group dynamics and the object relations theory. He was also part of the Tavistock group of psychologists who founded the Tavistock Institute.
25 Josef Breuer
Psychoanalyst and physician Josef Breuer inspired what later came to be known as Sigmund Freud’s cathartic method to treat mental ailments. His experiments with his patient Anna O. proved the therapeutic effect of the talking cure. He had also conducted research on the respiratory cycle and discovered the Hering-Breuer reflex.
26 Toni Wolff
Wilhelm Dilthey was a German psychologist, sociologist, historian, and hermeneutic philosopher. An ardent admirer of Friedrich Schleiermacher, Dilthey helped revive the former's works on hermeneutics. Wilhelm Dilthey is also credited with teaching future philosophers like Hans Lipps, Eduard Spranger, and Theodor Litt.
Gustav Fechner was a German physicist, philosopher, and experimental psychologist. A pioneer in the field of experimental psychology, Fechner is credited with founding psychophysics. Gustav Fechner inspired several philosophers and scientists like Jan Koenderink, David Heeger, and Farley Norman. In 1970, a crater on the Moon was named after him by the International Astronomical Union.
Chiefly known for his works on the diagnosis and understanding of schizophrenia, German psychiatrist Kurt Schneider published many papers on the subject, creating a list of the psychotic symptoms, today known as Schneiderian First-Rank Symptoms, to differentiate it from other forms of mental disorder. He also made significant contributions to personality disorders, coining term like endogenous depression and reactive depression.
43 Kurt Koffka
British physicist, meteorologist, mathematician, psychologist and pacifist Lewis Fry Richardson was the first to apply modern mathematical techniques of weather forecasting to predict weather accurately. He also pioneered the use of similar methods in studying reasons of wars and the way to stop them. He proposed the iterative method called modified Richardson iteration for solving a system of linear equations.
50 Fritz Heider
Initially aspiring to be an architect and then a lawyer, Fritz Heider gradually deviated toward psychology. The Austrian psychologist was a prominent figure of the Gestalt school. Considered one of the pioneers of interpersonal social psychology, he made significant contributions to the theories of attribution, balance, and motivation.