Co-reference and reasoning.

Co-reference occurs when two or more noun phrases refer to the same individual, as in the following inferential problem: Mark is kneeling by the fire or he is looking at the TV but not both. / Mark is kneeling by the fire. / Is he looking at the TV? In three experiments, we compared co-referential reasoning problems with problems referring to different individuals. Experiment 1 showed that co-reference improves accuracy. In Experiment 2, we replicated that finding and showed that co-reference speeds up both reading and inference. Experiment 3 showed that the effects of co-reference are greatest when the premises and the conclusion share co-referents. These effects led the participants to make illusory inferences--that is, to draw systematically invalid conclusions. The results are discussed in terms of the mental model theory of reasoning.