Reasoning, biases and dual processes: The lasting impact of Wason (1960)

Abstract

Wason (1960) published a relatively short experimental paper, in which he introduced the 2-4-6 problem as a test of inductive reasoning. This paper became one of the most highly cited to be published in the Quarterly Journal of Experimental Psychology and is significant for a number of reasons. First, the 2-4-6 task itself was ingenious and yielded evidence of error and bias in the intelligent participants who attempted it. Research on the 2-4-6 problem continues to the present day. More importantly, it was Wason's first paper on reasoning and one which made strong claims for bias and irrationality in a period dominated by rationalist writers like Piaget. It set in motion the study of cognitive biases in thinking and reasoning, well before the start of Tversky and Kahneman's famous heuristics and biases research programme. I also show here something for which Wason has received insufficient credit. It was Wason's work on this task and his later studies of his four card selection task that led to the first development of the dual process theory of reasoning which is so dominant in the current literature on the topic more than half a century later.

Keywords:

• Wason (1960)
• Reasoning; 2-4-6 task; Hypothesis testing; Confirmation bias

Notes

1 Short papers were normal at that time and single-experiment studies the norm.

2 28 citations in 2011, 30 citations in 2012, 21 citations in 2013 by 17 September of that year (Web of Science).

3 As an example, in the early 1970s Wason spent several months drafting and redrafting a (handwritten) book on the selection task. Dissatisfied with it, he binned his drafts. The book was never published. In common with several other comments about Wason in this article, this is based on my personal knowledge as his student, collaborator and friend, and cannot be documented in the orthodox academic manner.

4 Most researchers still accept this to be the correct solution, although it has been disputed, most notably by Oaksford and Chater (1994b).

5 I had been sceptical for many years as to whether the task showed a confirmation bias, although I did not discover Wetherick's paper until much later. I recall arguing with Peter Wason about this in the early 1970s, but he never gave any ground.

6 The review of work on the 2-4-6 problem has been of necessity both brief and selective, as my remit was to assess the overall impact of the Wason (1960) paper, which goes well beyond the invention of this task. Of the studies omitted, I point the reader interested in pragmatic influences on reasoning towards the interesting contributions of Van der Henst (2006) and Vallée-Tourangeau (2012).