Asset market bubbles and crashes are a major source of economic instability and inefficiency. Sometimes ascribed to animal spirits or irrational exuberance, their source remains imperfectly understood. Experimental methods can isolate systematic deviations from an asset's fundamental value in a...

We report an experiment that infers true overconfidence in relative ability through actions, as opposed to reported beliefs. Subjects choose how to invest earnings from a skill task when the returns depend solely upon risk, or both risk and relative placement, enabling joint estimation of...