Published online by Cambridge University Press: 19 May 2011
The new notation for mental-models theory proposed by Johnson-Laird and Byrne (1991; 1993) makes predictions that are inconsistent with those made previously by those authors. Notably, two frequently observed reasoning fallacies are not predicted by the theory. Moreover, the assumption made in the domain of syllogistic reasoning, that arbitrary numbers of individuals are used to represent premises, is also shown to cause problems for the prediction of problem difficulty.