Differential difficulty of categorical syllogisms

Abstract

Previous research with categorical syllogisms indicates that subject performance is better on valid syllogisms than on syllogisms which are indeterminate. The present study tested the hypothesis that the poorer performance on invalid syllogisms is a function of the disproportionate number of invalid syllogisms in the traditional syllogism task. Subjects may not expect so many invalid syllogisms and may be reluctant to draw so many nonpropositional conclusions. One group of subjects received the standard set of 19 valid and 45 invalid syllogisms, while a second group received a set of 35 valid and 29 invalid syllogisms. There were no significant differences between the groups on valid or invalid syllogisms, disconfirming the hypothesis. Several previous findings with categorical syllogisms were replicated. © 1976, The Psychonomic Society, Inc.. All rights reserved.