Three studies investigated the effects of concrete versus abstract wording and negative versus positive premises on the difficulty subjects had in solving several kinds of reasoning tasks. Subjects for all three studies were college undergraduates who received booklets containing either hypothetical, disjunctive, or linear syllogisms. Each booklet explained the difference between "valid" and "true" and gave an example of a valid untrue categorical syllogism. For each problem in the booklets, subjects were given two premises and instructed to write out a valid conclusion. Half the problems were constructed with positive premise components, and half included negatives; half used concrete nouns, and half used abstract words. After finishing the problems, subjects were asked to write whether they had used a special method for solving the problems and whether they had formed mental images. Subjects were also asked to specify their sex, year in school, and whether they had ever studied logic. Results showed that valid problems were easier to solve and that negation made the syllogisms harder, except for invalid hypothetical problems. The effect of concreteness depended on problem type: it facilitated hypothetical, hindered disjunctive, and had no impact on linear reasoning. (FL)