title: How two causes are different from one: the use of (un)conditional information in Simpson's paradox.
abstract: In a causally complex world, two (or more) factors may simultaneously be potential causes of an effect. To evaluate the causal efficacy of a factor, the alternative factors must be controlled for (or conditionalized on). Subjects judged the causal strength of two potential causes of an effect that covaried with each other, thereby setting up a Simpson's paradox--a situation in which causal judgments should vary widely depending on whether or not they are conditionalized on the alternative potential cause. In Experiments 1 (table format) and 2 (trial-by-trial format), the subjects did conditionalize their judgments for one causal factor on a known alternative cause. The subjects also demonstrated that they knew what information was needed to properly make causal judgments when two potential causes are available. In Experiment 3 (trial-by-trial), those subjects who were not told about the causal mechanism by which the alternative cause operated were less likely to conditionalize on it. However, the more a subject recognized the covariation between the alternative cause and the effect, the more the subject conditionalized on it. Such behavior may arise from the interaction between bottom-up and top-down processing.
authors.affiliation: Department of Psychology, University of Virginia, Charlottesville 22904-4400, USA. spellman@virginia.edu
authors.forename: B A
authors.initials: BA
authors.lastname: Spellman
authors.forename: C M
authors.initials: CM
authors.lastname: Price
authors.forename: J M
authors.initials: JM
authors.lastname: Logan
mesh_terms: D003657:Decision Making; D006801:Humans; D008960:Models, Psychological; D011582:Psychological Theory; D011897:Random Allocation