Social Leanring with Course Inference

We study social learning by boundedly rational agents. Agents take a decision in sequence, after observing their predecessors and a private signal. They are unable to understand their predecessors’ decisions in their finest details: they only understand the relation between the aggregate distribution of actions and the state of nature. We show that, in a continuous action space, compared to the rational case, agents put more weight on early signals. Despite this behavioral bias, beliefs converge to the truth. In a discrete action space, instead, convergence to the truth does not occur even if agents receive signals of unbounded precisions.

Social learning with local interactions

We study a simple dynamic model of social learning with local informational exter-nalities. There is a large population of agents, who repeatedly have to choose one, out of two, reversible actions, each of which is optimal in one, out of two, unknown states of the world. Each agent chooses rationally, on the basis of private information (s)he receives by a symmetric binary signal on the state, as well as the observation of the action chosen among their nearest neighbours. Actions can be updated at revision opportunities that agents receive in a random sequential order. Strategies are stationary, in that they do not depend on time, nor on location. We show that: if agents receive equally informative signals, and observe both neighbours, then the social learning process is not adequate and the process of actions converges ex-ponentially fast to a con�guration where some agents are permanently wrong; if agents are unequally informed, in that their signal is either fully informative or fully uninformative (both with positive probability), and observe one neighbour, then the social learning process is adequate and everybody will eventually choose the action that is correct given the state. Convergence, however, obtains very slowly, namely at rate pt: We relate the�findings with the literature on social learning and discuss the property of effciency of the information transmission mechanism under local interaction. <br><br> Keywords; social learning, bayesian learning, local informational external-ities, path dependence, consensus, clustering, convergence Rates

Herd Behavior in a Laboratory Financial Market

We study herd behavior in a laboratory Þnancial market where a sequence of subjects trades an asset whose value is unknown. In two treatments the price is updated according to a deterministic rule based on the order ßow, and in another it is updated by experimental participants. Theory predicts that agents should never herd. Our experimental results are in line with this prediction. Nevertheless, we observe a phenomenon that cannot be accounted for by the theory. In some cases, subjects decide not to use their private information and choose not to trade. In other cases, they ignore their private information to trade against the market (contrarian behavior). (JEL C92, D8, G14)

Endogenous Knowledge Spillovers and Labor Mobility in Industrial Clusters

Knowledge spillovers and labor mobility in industrial clusters are interrelated phenomena. A firm's knowledge is embodied in the entrepreneur and in the specialized workers. Knowledge can spill over from one firm to another through two channels: direct revelation from one entrepreneur to another and labor mobility. We show that, in equilibrium, an entrepreneur can disclose information to another in order to avoid labor poaching. The incentive of firms to disclose information voluntarily is one of the novel contributions of our paper. In the absence of information disclosure, spillovers can still occur through labor poaching. Labor poaching and voluntary disclosure of information can also occur simultaneously in equilibrium. We also provide a rationale for the localized character of the spillovers and for the limited geographical extensions of industrial clusters.Spillover, Industrial Cluster, Labor Mobility

Herd Behavior in Financial Markets: An Experiment with Financial Market Professionals

We study herd behavior in a laboratory ?nancial market with ?- nancial market professionals. An important novelty of the experi- mental design is the use of a strategy-like method. This allows us to detect herd behavior directly by observing subjects?decisions for all realizations of their private signal. In the paper, we compare two treatments - one in which the price adjusts to the order ?ow in such a way that herding should never occur, and one in which the presence of event uncertainty makes herding possible. In the ?rst treatment, traders herd seldom, in accordance with both the theory and previous experimental evidence on student subjects. A proportion of traders, however, engage in contrarianism, something not accounted for by the theory. In the second treatment, on the one hand, the proportion of herding decisions increases, but not as much as the theory would sug- gest; on the other hand, contrarianism disappears altogether. In both treatments, in contrast with what theory predicts, subjects sometimes prefer to abstain from trading, which a¤ects the process of price discovery negatively.

Herd Behavior in Financial Markets: An Experiment with Financial Market Professionals

We study herd behavior in a laboratory financial market with financial market professionals. An important novelty of the experimental design is the use of a strategy-like method. This allows us to detect herd behavior directly by observing subjects’ decisions for all realizations of their private signal. In the paper, we compare two treatments: one in which the price adjusts to the order flow in such a way that herding should never occur, and one in which the presence of event uncertainty makes herding possible. In the first treatment, subjects herd seldom, in accordance with both the theory and previous experimental evidence on student subjects. A proportion of sub jects, however, engage in contrarianism, something not accounted for by the theory. In the second treatment, the proportion of herding decisions increases, but not as much as the theory would suggest. Moreover, contrarianism disappears altogether. In both treatments, in contrast with what theory predicts, subjects sometimes prefer to abstain from trading, which affects the process of price discovery negatively.Herding, Contrarianism, Financial Market Professionals

When half the truth is better than the truth: A Theory of aggregate information cascades

We introduce a new model of aggregate information cascades where only one of two possible actions is observable to others. When called upon, agents (who decide in some random order that they do not know) are only informed about the total number of others who have chosen the observable action before them. This informational structure arises nat- urally in many applications. Our most important result is that only one type of cascade arises in equilibrium, the aggregate cascade on the observable action. A cascade on the unobservable action never arises. Our results may have important policy consequences. Central agencies, for example in the health sector, may optimally decide to withhold in- formation from the public.

No-Trade in the Laboratory

We test the no-trade theorem in a laboratory financial market where subjects can trade an asset whose value is unknown. Subjects receive clues on the asset value and then set a bid and an ask at which they are willing to buy or to sell from the other participants. In treatments with no gains from trade, theory predicts no trading activity, whereas, in treatments with gains, trade becomes theoretically possible. Our experimental results show that subjects fail to reach the no-trade equilibrium by pure introspection, but they learn to approach it over time,through market feedback and learning.no-trade theorem, experiment

No-Trade in the Laboratory

We test the no-trade theorem in a laboratory nancial market where subjects can trade an asset whose value is unknown. Subjects receive clues on the asset value and then set a bid and an ask at which they are willing to buy or to sell from the other participants. In treatments with no gains from trade, theory predicts no trading activity, whereas, in treatments with gains, trade becomes theoretically possible. Our experimental results show that subjects fail to reach the no-trade equilibrium by pure introspection, but they learn to approach it over time, through market feedback and learning.