- 1946 – Karl Groos, German psychologist and philosopher (b. 1861).
- 1998 – David McClelland, American psychologist and academic (b. 1917).
Karl Groos (10 December 1861 to 27 March 1946, in Tübingen) was a philosopher and psychologist who proposed an evolutionary instrumentalist theory of play. His 1898 book on The Play of Animals suggested that play is a preparation for later life.
Groos was full Professor of philosophy in Gießen, Basel and 1911-1929 in Tübingen.
His main idea was that play is basically useful, and so it can be explained by the normal process of evolution by natural selection. When animals ‘play’ they are practising basic instincts, such as fighting, for survival. This is translated from the original as “pre-tuning”. Despite this insight, Groos’ work is seldom read today, and his connection of play with aesthetics has been termed “misguided”. Another area of study was the psychology of literature, including statistical analysis.
Among his scholars is the German philosopher Willy Moog (1888-1935) (doctorate on Goethe supervised by Karl Groos in Gießen 1909).
David Clarence McClelland (20 May 1917 to 27 March 1998) was an American psychologist, noted for his work on motivation Need Theory.
He published a number of works between the 1950s and the 1990s and developed new scoring systems for the Thematic Apperception Test (TAT) and its descendants. McClelland is credited with developing Achievement Motivation Theory, commonly referred to as “need for achievement” or n-achievement theory. A Review of General Psychology survey published in 2002, ranked McClelland as the 15th most cited psychologist of the 20th century.