Proceedings of the Annual Meeting of the Cognitive Science Society

How do people tell the difference between random and nonrandom events? What affects peoples understanding of ran-domness? In two experiments, we investigated the role of two characteristics of a sequencealternation rate and numberof occurrencein peoples perception of randomness. We presented participants with a pair of binary sequences of length 6(e.g., OXOXXO vs. XOXXXX) and asked them to evaluate which of the two was more likely to occur. In Experiment1, we examined how participants randomness perception changed as the difference in alternation rate and the differencein the number of occurrence changed. In Experiment 2, we further examined whether participants exhibited differentialreliance on alternation rate and number of outcomes. Results suggest that people exhibit differential reliance on alternationrate and number of occurrence. When the two characteristics are in conflict, people tend to rely more on the alternationrate in their randomness judgement.