Essays on Contract Theory and Behavioral Economics

This thesis is a collection of essays on contract theory and behavioral economics. Chapter 1 proposes a model of choice under risk based on imperfect memory and self-deception. The model assumes that people have preferences over their own attributes and can, to some extent, manipulate their memories. It leads to a non-expected utility representation and provides a unified explanation for several empirical regularities: non-linear probability weights, smallstakes risk aversion, regret and the competence hypothesis. It also leads to endowment and sunk cost effects. The model implies that behavior will converge to the one predicted by expected utility theory after a choice has been made a sufficiently large number of times. Chapter 2 develops a model of competition with non-exclusive contracts in a market where consumers are time-inconsistent. Non-exclusivity creates a stark asymmetry between immediatecosts goods and immediate-rewards goods. In the former, non-exclusivity does not affect the equilibrium and, when consumers are sophisticated, the efficient allocation is achieved. When consumers are partially naive, the optimal sales tax may be either positive or negative and depends on parameters that are hard to estimate. In the case of immediate-rewards goods, however, the equilibrium features marginal-cost pricing and is always Pareto inefficient. Moreover, the optimal tax does not depend on the consumers' degree of naivete and is a function of parameters that are easy to assess. Chapter 3 is based on a joint work with Aloisio Araujo and Humberto Moreira. It considers a job-market signaling model where signals convey two pieces of information. The model is employed to study countersignalling (signals nonmonotonic in ability) and the GED exam. A result of the model is that countersignalling is more likely to occur in jobs that require a combination of skills that differs from the combination used in the schooling process. The model also produces testable implications consistent with evidence on the GED: (i) it signals both high cognitive and low noncognitive skills and (ii) it does not affect wages. Chapter 4, which is also based on joint work with Aloisio Araujo and Humberto Moreira, characterizes incentive-compatibility in models where types are multidimensional and the singlecrossing condition may not hold. This characterization is used to obtain the optimal contracts in multidimensional screening as well as the equilibria in multidimensional signaling models. Then, I determine the implications of signaling and screening models when the single-crossing condition is violated. I show that the unique robust prediction of signaling is the monotonicity of transfers in (costly) actions. Any function from the space of types to the space of actions and an increasing transfer schedule can be rationalized as an equilibrium profile of many signaling models. Apart from the monotonicity of transfers in actions, I obtain an additional necessary and sufficient condition in the case of screening. In one-dimensional models, this condition states that the principal's profit as a function of the agent's type must grow at a higher rate under asymmetric information than under symmetric information. Thesis Supervisor: Muhamet Yildiz Title: Professor of Economics Thesis Supervisor: Bengt Holmstr6m Title: Paul A. Samuelson Professor of Economics