An Austrian medical doctor, psychotherapist, and founder of the school of individual psychology.[2] His emphasis on the importance of feelings of inferiority,[3] the inferiority complex, is recognized as an isolating element which plays a key role in personality development.[4] Alfred Adler considered a human being as an individual whole, therefore he called his psychology "Individual Psychology"

An Austrian neurologist and the founder of psychoanalysis, a clinical method for treating psychopathology through dialogue between a patient and a psychoanalyst.

An American psychologist who in 1955 developed Rational Emotive Behavior Therapy (REBT). He held MA and PhD degrees in clinical psychology from Columbia University and the American Board of Professional Psychology (ABPP). He also founded and was the President of the New York City-based Albert Ellis Institute for decades. He is generally considered to be one of the originators of the cognitive revolutionary paradigm shift in psychotherapy and an early proponent of cognitive-behavioral therapies.