We develop a theory of how an agent makes basic multiproduct consumption decisions in the presence of taste, consumption opportunity, and price shocks that are costly to attend to. We establish that the agent often simplifies her choices by restricting attention to a few important considerations, which depend on the decision at hand and affect her consumption patterns in specific ways. If the agent’s problem is to choose the consumption levels of many goods with different degrees of substitutability, then she may create mental budgets for more substitutable products (e.g., entertainment). In some situations, it is optimal to specify budgets in terms of consumption quantities, but when most products have an abundance of substitutes, specifying budgets in terms of nominal spending tends to be optimal. If the goods are complements, in contrast, then the agent may—consistent with naive diversification—choose a fixed, unconsidered mix of products. And if the agent’s problem is to choose one of multiple products to fulfill a given consumption need (e.g., for gasoline or a bed), then it is often optimal for her to allocate a fixed sum for the need.

We initiate the study of naïveté-based discrimination, the practice of conditioning offers on external information about consumers’ naïveté. Knowing that a consumer is naive increases a monopolistic or competitive firm's willingness to generate inefficiency to exploit the consumer's mistakes, so naïveté-based discrimination is not Pareto-improving, can be Pareto-damaging, and often lowers total welfare when classical preference-based discrimination does not. Moreover, the effect on total welfare depends on a hitherto unemphasized market feature: the extent to which the exploitation of naive consumers distorts trade with different types of consumers. If the distortion is homogeneous across naive and sophisticated consumers, then under an arguably weak and empirically testable condition, naïveté-based discrimination lowers total welfare. In contrast, if the distortion arises only for trades with sophisticated consumers, then perfect naïveté-based discrimination maximizes social welfare, although imperfect discrimination often lowers welfare. If the distortion arises only for trades with naive consumers, then naïveté-based discrimination has no effect on welfare. We identify applications for each of these cases. In our primary example, a credit market with present-biased borrowers, firms lend more than is socially optimal to increase the amount of interest naive borrowers unexpectedly pay, creating a homogeneous distortion. The condition for naïveté-based discrimination to lower welfare is then weaker than prudence.

We develop a model that fleshes out, extends, and modifies existing models of referencedependent preferences and loss aversion while accomodating most of the evidence motivating these models. Our approach makes reference-dependent theory more broadly applicable by avoiding some of the ways that prevailing models—if applied literally and without ancillary assumptions—make variously weak and incorrect predictions. Our model combines the reference-dependent gain-loss utility with standard economic “consumption utility ” and clarifies the relationship between the two. Most importantly, we posit that a person’s reference point is her recent expectations about outcomes (rather than the status quo), and assume that behavior accords to a personal equilibrium: The person maximizes utility given her rational expectations about outcomes, where these expectations depend on her own anticipated behavior. We apply our theory to consumer behavior, and emphasize that a consumer’s willingness to pay for a good is endogenously determined by the market distribution of prices and how she expects to respond to these prices. Because a buyer’s willingness to buy depends on whether she anticipates buying the good, for a range of market prices there are multiple personal equilibria. This multiplicity disappears when the consumer is sufficiently uncertain about the price she will face. Because paying more than she anticipated induces a sense of loss in the buyer, the lower the prices at which she expects to buy the lower will be her willingness to pay. In some situations, a known stochastic decrease in prices can even lower the quantity demanded.

We identify a competition-policy-based argument for regulating the secondary features of complex or complexly priced products when consumers have limited attention. Limited attention implies that consumers can only “study” a small number of complex products in full, while—by failing to check secondary features—they can superficially “browse” more. Interventions limiting ex post consumer harm through safety regulations, caps on certain fees, or other methods induce consumers to do more or more meaningful browsing, enhancing competition. We show that for a pro-competitive effect to obtain, the regulation must apply to the secondary features, and not to the total price or value of the product. As an auxiliary positive prediction, we establish that because low-value consumers are often more likely to study—and therefore less likely to browse—than high-value consumers, the average price consumers pay can be increasing in the share of low-value consumers. We discuss applications of our insights to health-insurance choice, the European Union’s principle on unfair contract terms, food safety in developing countries, and the shopping behaviour of (and prices paid by) low-income and high-income consumers.

We analyse conditions facilitating profitable deception in a simple model of a competitive retail market. Firms selling homogenous products set anticipated prices that consumers understand and additional prices that naive consumers ignore unless revealed to them by a firm, where we assume that there is a binding floor on the anticipated prices. Our main results establish that “bad” products (those with lower social surplus than an alternative) tend to be more reliably profitable than “good” products. Specifically, (1) in a market with a single socially valuable product and sufficiently many firms, a deceptive equilibrium—in which firms hide additional prices—does not exist and firms make zero profits. But perversely, (2) if the product is socially wasteful, then a profitable deceptive equilibrium always exists. Furthermore, (3) in a market with multiple products, since a superior product both diverts sophisticated consumers and renders an inferior product socially wasteful in comparison, it guarantees that firms can profitably sell the inferior product by deceiving consumers. We apply our framework to the mutual fund and credit card markets, arguing that it explains a number of empirical findings regarding these industries.

We develop a model of multi-dimensional misspecified learning in which an overconfident agent learns about groups in society from observations of his and others’ successes. We show that the average person sees his group relative to other groups too positively, and this in-group bias exhibits systematic comparative-statics patterns. First, a person is most likely to have negative opinions about other groups he competes with. Second, while information about another group’s achievements does not lower a person’s prejudice, information about economic or social forces affecting the group can, and personal contact with group members has a beneficial effect that is larger than in classical settings. Third, the agent’s beliefs are subject to “bias substitution”, whereby forces that decrease his bias regarding one group tend to increase his biases regarding unrelated other groups.

We develop a model of fragile self-esteem—self-esteem that is vulnerable to objectively unjustified swings—and study its implications for choices that depend on, or are aimed at enhancing or protecting, one’s self-view. In our framework, a person’s self-esteem is determined by sampling his memories of ego-relevant outcomes in a fashion that in turn depends on how he feels about himself, potentially creating multiple fragile “self-esteem personal equilibria.” Self-esteem is especially likely to be fragile, as well as unrealistic in either the positive or the negative direction, if being successful is important to the agent. A person with a low self-view might exert less effort when success is more important. An individual with a high self-view, in contrast, might distort his choices to prevent a collapse in self-esteem, with the distortion being greater if his true ability is lower. We discuss the implications of our results for mental well-being, education, job search, workaholism, and aggression.

Many consumers care about climate change and other externalities associated with their purchases. We analyze the behavior and market effects of such “socially responsible consumers” in three parts. First, we develop a flexible theoretical framework to study competitive equilibria with rational consequentialist consumers. In violation of price taking, equilibrium feedback nontrivially dampens the impact of a person’s consumption on aggregate consumption, undermining the motive to mitigate. This leads to a new type of market failure, where even consumers who fully “internalize the externality” overconsume externality-generating goods. At the same time, socially responsible consumers change the relative effectiveness of taxes, caps, and other policies in lowering the externality. Second, since consumer beliefs about and preferences over their market impacts play a crucial role in our framework, we investigate them empirically via a tailored survey. Consistent with our model, consumers are often consequentialist, and many believe that they have a dampened impact on aggregate consumption. Inconsistent with our model, however, we also find many respondents who expect to have a one-to-one impact on aggregate consumption. Third, therefore, we analyze how such “naive” consumers modify our theoretical conclusions. They consume less than rational consumers in a single-good economy, but may consume more in a multigood economy with cross-market spillovers. A mix of naive and rational consumers may yield the worst outcomes.