title: Normative and descriptive accounts of the influence of power and contingency on causal judgement.
abstract: The power PC theory (Cheng, 1997) is a normative account of causal inference, which predicts that causal judgements are based on the power p of a potential cause, where p is the cause-effect contingency normalized by the base rate of the effect. In three experiments we demonstrate that both cause-effect contingency and effect base-rate independently affect estimates in causal learning tasks. In Experiment 1, causal strength judgements were directly related to power p in a task in which the effect base-rate was manipulated across two positive and two negative contingency conditions. In Experiments 2 and 3 contingency manipulations affected causal estimates in several situations in which power p was held constant, contrary to the power PC theory's predictions. This latter effect cannot be explained by participants' conflation of reliability and causal strength, as Experiment 3 demonstrated independence of causal judgements and confidence. From a descriptive point of view, the data are compatible with Pearce's (1987) model, as well as with several other judgement rules, but not with the Rescorla-Wagner (Rescorla & Wagner, 1972) or power PC models.
authors.affiliation: Universidad de Granada, Spain.
authors.forename: José C
authors.initials: JC
authors.lastname: Perales
authors.forename: David R
authors.initials: DR
authors.lastname: Shanks
mesh_terms: D000293:Adolescent; D000328:Adult; D003071:Cognition; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D008960:Models, Psychological