Reasoning about a Rule

  title={Reasoning about a Rule},
  author={Peter Cathcart Wason},
  journal={Quarterly Journal of Experimental Psychology},
  pages={273 - 281}
  • P. Wason
  • Published 1 August 1968
  • Psychology
  • Quarterly Journal of Experimental Psychology
Two experiments were carried out to investigate the difficulty of making the contra-positive inference from conditional sentences of the form, “if P then Q.” This inference, that not-P follows from not-Q, requires the transformation of the information presented in the conditional sentence. It is suggested that the difficulty is due to a mental set for expecting a relation of truth, correspondence, or match to hold between sentences and states of affairs. The elicitation of the inference was not… 

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