A Systematic Test of the Independence Axiom Near Certainty

A large literature has documented violations of expected utility consistent with a preference for certainty (the "certainty effect"). We design a laboratory experiment to investigate the role of the certainty effect in explaining violations of the independence axiom. We use lotteries spanning over the entire probability simplex to detect violations systematically. We find that violations of independence consistent with the reverse certainty effect are much more common than violations consistent with the certainty effect. Results hold as we test robustness along two dimensions: varying the mixing lottery and moving slightly away from certainty.