Conjunctions are easier than disjunctions: A study of logical reasoning problems in the GRE

We report three experiments corroborating a prediction of the theory of mental models about reasoning. In realistic problems deriving from those used in the Graduate Record Examination (GRE), logically untrained individuals are able to cope better with conditional assertions, which have only a single explicit mental model, than with disjunctive assertions, which have multiple explicit mental models. The experiments showed that a manipulation of a sentence in the text of the problems had only a marginal effect, whereas a manipulation of the response options – whether they were both conditionals or both disjunctions – had robust effects both on the accuracy of performance and the latency of response.