Causal Strength Account for Violations of the Screening-off Rule in Causal Reasoning

Abstract As a core of Causal Bayes networks, Screening-off rule is usually violated by people. Two experiments were conducted to investigate causal strength’s role in the violations of screening-off rule. Experiment 1 tested whether participants would follow the screening-off rule by examining the probability judgment of target nodes which would be influenced by the state of non-target nodes in common cause and chain models. Experiment 2 examined whether the probability judgment of target nodes would be influenced by causal strength judgment of their common cause in the common cause model (or of the middle node in the chain model). Both experiments used binary variables. Results showed that participants’ causal inferences increased with their perceived causal strength which grew with the presence proportion of other causal-related variables. Findings suggested that the causal strength explanation could offer the best prediction for people’s causal inferences, indicating people were sensitive to explicit causal strength of events and made causal inferences according to the strength. Thus, people’s causal inferences may not violate the screening-off rule.