title: Modeling the effects of argument length and validity on inductive and deductive reasoning.
abstract: In an effort to assess models of inductive reasoning and deductive reasoning, the authors, in 3 experiments, examined the effects of argument length and logical validity on evaluation of arguments. In Experiments 1a and 1b, participants were given either induction or deduction instructions for a common set of stimuli. Two distinct effects were observed: Induction judgments were more affected by argument length, and deduction judgments were more affected by validity. In Experiment 2, fluency was manipulated by displaying the materials in a low-contrast font, leading to increased sensitivity to logical validity. Several variants of 1-process and 2-process models of reasoning were assessed against the results. A 1-process model that assumed the same scale of argument strength underlies induction and deduction was not successful. A 2-process model that assumed separate, continuous informational dimensions of apparent deductive validity and associative strength gave the more successful account.
authors.affiliation: Department of Psychology, University of Massachusetts, Box 37710, Amherst, MA 01003, USA. caren@psych.umass.edu
authors.forename: Caren M
authors.initials: CM
authors.lastname: Rotello
authors.forename: Evan
authors.initials: E
authors.lastname: Heit
mesh_terms: D006801:Humans; D007600:Judgment / Q000502:physiology*; D008128:Logic; D008606:Mental Processes / Q000502:physiology*; D008960:Models, Psychological; D008962:Models, Theoretical; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D015203:Reproducibility of Results