Human Communication Research Centre
Edinburgh University
k.stenning@ed.ac.uk
Institute for Logic, Language and Computation
University of Amsterdam
michiell@wins.uva.nl
We discuss the various explanations that have been offered to account for subjects' behaviour in Wason's famous selection task, and find them wanting. We argue that what is lacking is a good understanding of a subject's semantics for the key expressions involved, and an understanding of how this semantics is affected by the demands the task puts upon the subject's cognitive system.