Execution of complex cognitive tasks is often analyzed as an exercise of information acquisition and belief updating. We challenge this view in the context of a non-incremental task, namely, the knapsack problem. First, we provide a theoretical argument why Bayesian updating makes little sense...

We propose a Marshallian model for price and allocation adjustments in parallel continuous double auctions. Agents quote prices that they expect will maximize local utility improvements. The process generates Pareto optimal allocations in the limit. In experiments designed to induce CAPM...

Many real-world markets are competitive only in smalls, taken to mean that price taking applies only to small orders. Starting from this observation, a theory of equilibration is derived where orders are optimal merely in a local sense. Prices are assumed to adjust in the direction of the order...

An alternative explanation is suggested for the erratic behavior of otherwise significant z-statistics in tests of the profitability of simple trading strategies. It is not attributed to time-varying risk premia, but, instead, to a failure of the distributional theory in inefficient markets. In...

Consider the Rational Expectations price history of an Arrow-Debreu security that matures in the money: p(1), p(2), ..., p(T). Past information can be used to predict the return (p(t+1)-p(t))/p(t). Now consider a simple alternative performance measure: (p(t+1)-p(t))/p(t+1). It differs from the...

We study the Efficient Markets Hypothesis (EMH) in a setting where information heterogeneity emerges because securities valuation requires solving an NP-hard problem. We demonstrate experimentally that the quality of prices deteriorates substantially as computational complexity increases....

Experiments constitute an indispensable tool to validate the building blocks of the theories which economists use not only to interpret events in the real world but also to inform regulation and economic policy. This is especially true in the context of multiple, interacting markets, which is...

We introduce an experimental design where arbitrage opportunities emerge reliably and repeatedly. We observe significantly higher sell-side than buy-side arbitrage opportunities. We study ways to mitigate them. Relaxing margin requirements, shortsale restrictions, or both have neither...