Peter Cathcart Wason

Wason created the Selection Task, also known as the 4-card task, in 1966. In this task, participants were exposed to four cards on a table, and given a rule by the experimenter. The participants were then told to choose just cards to determine whether the rule given to them by the experimenter was true or false. As Wason expected, a majority of participants failed to answer the question correctly. Only ten percent of participants solved this task correctly. The confirmation bias played a large part in this result, as participants usually chose cards to confirm their hypothesis, instead of eliminating it.

In 1960 Wason developed the first of many tasks he would devise to reveal the failures of human reasoning. The “2-4-6” task was the first experiment that showed people to be illogical and irrational. In this study, subjects were told that the experimenter had a rule in mind that only applied to sets of threes. The “2-4-6” rule the experimenter had in mind was “any ascending sequence”. In most cases, subjects not only formed hypotheses that were more specific than necessary, but they also only tested positive examples of their hypothesis. Wason was surprised by the large number of subjects who failed to get the task correct. The subjects failed to test instances inconsistent with their own hypothesis, which further supported Wason’s hypothesis of confirmation bias.

Peter Wason endured his schooling, which was marked by consistent failure. With the beginning of World War II, Wason completed officer training at Sandhurst, and then served as a liaison officer for the 8th Armoured Brigade, by then an independent brigade. Wason returned home in 1945, having been released from his duties of being an officer due to extreme injuries. Wason then pursued more academic ventures by studying English at Oxford in 1948, and continued on to become a lecturer at the University of Aberdeen. After the realization that he did not really prefer English, and actually found it quite boring, Wason returned to Oxford University to obtain a master's degree in psychology in 1953, and then a doctorate in 1956 from University College London. He remained teaching at University College London until his retirement in the early 1980s.

Peter Cathcart Wason (22 April 1924 – 17 April 2003) was a cognitive psychologist at University College, London who pioneered the Psychology of Reasoning. He progressed explanations as to why people make certain consistent mistakes in logical reasoning. He designed problems and tests to demonstrate these processes, for example the Wason selection task, the THOG problem and the 2-4-6 problem. He also coined the term "confirmation bias" to describe the tendency for people to immediately favor information that validates their preconceptions, hypotheses and personal beliefs regardless of whether they are true or not.

Wason was born in Bath Somerset on 22 April 1924, and died at seventy-nine in Wallingford, Oxfordshire on 17 April 2003. Peter Wason was the grandson to Eugene Wason, and the son to Eugene Monier and Kathleen (Woodhouse) Wason. Wason married Marjorie Vera Salberg in 1951, and the couple had two children, Armorer and Sarah. His uncle was Lieutenant General Sydney Rigby Wason.