title: People think about what is true for conditionals, not what is false: only true possibilities prime the comprehension of "if".
abstract: We report the results of two priming experiments that examine the comprehension of conditionals--for example, "if there are apples then there are oranges"--and biconditionals--for example, "if and only if there are apples then there are oranges". The first experiment showed that participants read a biconditional faster when it was primed by a true possibility, "there were apples and there were oranges" than when it was primed by a false possibility, "there were no apples and there were oranges"; a conditional was primed equally by both possibilities. The second experiment showed that participants read the negated-antecedent conjunction faster when it was primed by a conditional than when it was primed by a biconditional; the affirmative conjunction was primed equally by both connectives. The experiments show that (a) when people understand "if A then B", they access the true possibilities, "A and B", and "not-A and B", and (b) when they understand "if and only if A then B" they access "A and B", but they do not access "not-A and B". We discuss their implications for current theories of reasoning.
authors.affiliation: Departamento de Psicología Cognitiva, University of La Laguna, Tenerife, Spain. oespinom@ull.es
authors.forename: Orlando
authors.initials: O
authors.lastname: Espino
authors.forename: Carlos
authors.initials: C
authors.lastname: Santamaria
authors.forename: Ruth M J
authors.initials: RM
authors.lastname: Byrne
mesh_terms: D000704:Analysis of Variance; D032882:Comprehension; D003213:Conditioning, Psychological / Q000502:physiology*; D006801:Humans; D008960:Models, Psychological; D011340:Problem Solving / Q000502:physiology*; D011578:Psycholinguistics; D011594:Psychometrics; D011930:Reaction Time; D011932:Reading; D013850:Thinking / Q000502:physiology*