This collection of essays focuses on three reasoning problems devised by Peter Wason - the selection task, the 2-4-6 task, and the THOG problem.

Creating a psychology of reasoning - the contribution of Peter Wason, J.St.B.T. Evans, S.E. Newstead; the effects of rule clarification, decision justification and selection instructions on Wason's abstract selection task, R. A. Griggs; content effects in Wason's selection task, R.L. Dominowski; pragmatic reasoning about human voluntary action - evidence from Wason's selection task, K.J. Holyoak, P.W. Cheng; deontic reasoning, K.I. Manktelow, D. E. Over; inference and mental models, P.N. Johnson-Laird; relevance and reasoning, J.St.B.T. Evans; the abstract selection - thesis, antithesis and synthesis, D.W. Green; finding logic in human reasoning requires looking in the right places - a mental logic view of logical reasoning tasks, D.P. O'Brien; hypothesis testing, M.E. Gorman; scientific reasoning, R.D. Tweney, S.T. Chitwood; the THOG problem and its implications for human reasoning, S.E. Newstead, V. Girotto, P. Legrenzi; creativity in research, P.C. Wason.