ORDERING OF INFORMATION IN CONDITIONAL REASONING

Two experiments are reported in which participants are asked to evalua te computer-presented conditional syllogisms consisting of a major pre mise (conditional rule), a minor premise and a conclusion. As an examp le the modus tollens inference with an affirmative conditional has the form if p then q, not-q therefore nat-p. In these experiments, partic ipants were asked to judge the validity of four types of conditional s yllogisms with four types of conditional rule in which the presence an d absence of negated components was varied. In Expt 1, half of the par ticipants received problems with the conclusion presented prior to the premises, and half in the usual order. Experiment 2 combined this var iable with a second: standard or reversed order of major and minor pre mises. Both manipulations substantially reduced the effects of the neg ative conclusion bias which is typically observed in this paradigm. Th e findings are discussed with respect to the debate between mental mod els and mental logic accounts of conditional inference.