Reasoning with exclusive disjunction arguments

An experiment was performed to determine the effects of negation in the major premise and/or conclusion of exclusive disjunction arguments on adults' abilities to apply two basic principles of exclusive disjunction. The component of the disjunctive premise that was referred to in the minor premise was varied systematically so that the influence of this factor could also be explored. The results indicated that arguments involving the confirmation of one of the components of the disjunctive premise followed by the denial of the other component of this premise were easier to evaluate than those in which this confirmation/denial sequence was reversed. In addition, arguments in which the disjunctive premise had two affirmative components were easier than those in which the disjunctive premise contained at least one negative component, but arguments with affirmative conclusions were more difficult than those with negative conclusions. Most importantly, an examination of subjects' errors and their response patterns revealed primitive response tendencies that paralleled those reported in previous studies of adults' propositional reasoning abilities.