Bayesian orthodoxy posits a tight relationship between conditional probability and updating. Namely, the probability of an event "A" after learning "B" should equal the conditional probability of "A" given "B" prior to learning "B". We examine whether ordinary judgment conforms to the orthodox view. In three experiments we found substantial…

In three shape-constancy experiments, 4- and 7-year olds viewed a circular disc oriented at a slant. All subjects exaggerated circularity of the disc when they knew the object was a circle. Findings suggest that knowledge of reality contaminates judgments of appearance in circle task and this is the same bias that features in realist errors in…