Botond Kőszegi

Research Director

Botond Kőszegi


Botond Kőszegi serves as briq Research Director and is Professor of Economics (on leave) at the University of Bonn and Central European University. He was previously Professor at UC Berkeley. He received a BA in mathematics from Harvard University, and a PhD in economics from MIT. He has published extensively on behavioral-economics topics – including several lead articles – in top journals. The diverse topics of Kőszegi’s research include the consumption of regulation of harmful products, self-image and anticipatory utility, reference-dependent preferences and loss aversion, markets for deceptive products, behavioral contract theory, and misguided learning. He has received European Research Council Grants in 2012 and 2018, and the Jahnsson Award, a biennial award for the best economist in Europe under the age of 45, in 2015.

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Heidhues, P., Köster, M., & Kőszegi, B. (2023). Steering Fallible Consumers. Economic Journal, 133(652), 1430-1465. Described (in German).

working papers

Many consumers care about climate change and other broad externalities. We model and analyze the market behavior of such “socially responsible consumers,” derive properties of the resulting competitive equilibria, and study the effectiveness of different policies. In violation of price taking, a vanishingly small consumer cares about her impact on the behavior of the rest of the market to a non-vanishing extent. That impact on others endogenously dampens the consumer’s direct effect on the externality, undermining responsible behavior. Dampening implies that even if all consumers value the externality like the social planner, they mitigate too little in any equilibrium, and may coordinate on the worst of multiple equilibria. To motivate consumers to lower the externality in a closed economy, a unit tax is superior to a cap-and-trade system, but there are policies that are better than a tax. Furthermore, under trade with a large or very polluting partner, a cap is better than a tax. When there are two products that are perfect substitutes in consumption but generate different externalities, there is always an equilibrium in which the products have the same price and consumers are indifferent between them. Under conditions we identify, this selfish equilibrium is the unique equilibrium. In a selfish equilibrium, a cap and a unit tax on the dirty product can achieve the same outcomes. In non-selfish equilibria, a proportional subsidy on the clean product dominates both a unit tax and a cap.
We model an agent who stubbornly underestimates how much his behavior is driven by undesirable motives, and, attributing his behavior to other considerations, updates his views about those considerations. We study general properties of the model, and then apply the framework to identify novel implications of partially naive present bias. In many stable situations, a partially naive present-biased agent appears realistic in that he eventually predicts his behavior well. His unrealistic self-view does, however, manifest itself in several other ways. First, in basic settings he always comes to act in a more present-biased manner than a sophisticated agent. Second, he systematically mispredicts how he will react when circumstances change, such as when incentives for forward-looking behavior increase or he is placed in a new, ex-ante identical environment. Third, he follows empirically realistic addiction-like consumption dynamics that he does not anticipate. Fourth, he holds beliefs that — when compared to those of other agents — display puzzling correlations between logically unrelated issues. Our model implies that existing empirical tests of sophistication in intertemporal choice can reach incorrect conclusions. Indeed, we argue that some previous findings are more consistent with our model than with a model of correctly specified learning.
We develop models of markets with procrastinating consumers where competition operates — or is supposed to operate — both through the initial selection of providers and through the possibility of switching providers. As in other work, consumers fail to switch to better options after signing up with a firm, so at that stage they exert little downward pressure on the prices they pay. Unlike in other work, however, consumers are not keen on starting with the best available offer, so price competition fails at this stage as well. In fact, a competition paradox results: an increase in the number of firms or the intensity of marketing increases the frequency with which a consumer receives switching offers, so it facilitates procrastination and thereby potentially raises prices. By implication, continuous changes in marketing costs can, through a self-reinforcing process, lead to discontinuous changes in market outcomes. Sign-up deals do not serve their classically hypothesized role of returning ex-post profits to consumers, and in some cases even exacerbate the failure of price competition. Consumer procrastination thus emerges as a novel source of competition failure that applies in situations where other theories of competition failure do not.
By injecting a single non-classical assumption, overconfidence, into a bare-bones model of how an agent learns from social observations, we explain key stylized facts about social beliefs and factors that influence them, and make additional novel predictions. First, the agent has self-centered views about discrimination: he believes in discrimination against any group he is in more than an outsider does. Second, the agent is subject to in-group bias: the greater is his “index of similarity” with an individual, the more positively he evaluates the individual. Third, these biases are increasing in the agent’s overconfidence. Fourth, the biases are sensitive to how he divides society into groups when evaluating outcomes, so changing his way of thinking on this matter can lower his biases. Fifth, however, only specific types of information are helpful in debiasing the agent; e.g., giving him more accurate information about himself increases all his biases, and better information about someone else helps only if it is direct personal information about the individual’s quality. Sixth, the agent is prone to “bias substitution,” implying that the introduction of a new competitor group leads him to develop a negative opinion of the new group but positive opinions of other groups. Due to its unique blend of predictions, the model is consistent with much evidence invoked for either the statistical or the taste-based theory of discrimination against the other. Methodologically, our analysis is made possible by a novel explicit characterization of long-run beliefs in general high-dimensional misspecified learning models with normal exogenous signals.
We analyze the implications of increases in the selection of, and information about, derivative financial products in a model in which investors neglect informational differences between themselves and issuers. We assume that investors receive information that is noisy and inferior to issuers’ information, and that issuers can select the set of underlying assets when designing a security. In contrast to the received wisdom that diversification is helpful, we show that when custom-designed diversification across a large number of underlying assets is possible, then expected utility approaches negative infinity. Even beyond this limiting case, any expansion in choice induced by either an increase in the maximum number of assets underlying a security, or an increase in the number of assets from which the underlying can be selected, Pareto-lowers welfare. Furthermore, under reasonable conditions an improvement in investor information Pareto-lowers welfare by giving investors the false impression that they can spot good deals. An increase in competition between issuers does not increase welfare, and even increases investors’ incentive to acquire welfare-reducing information. Restricting the set of underlying assets the issuer can use—a kind of standardization—raises welfare, and once this policy is adopted, increasing investor information becomes beneficial.

refereed publications

Online intermediaries with information about a consumer’s tendencies often “steer” her toward products she is more likely to purchase. We analyze the welfare implications of this practice for “fallible” consumers, who make statistical and strategic mistakes in evaluating offers. The welfare effects depend on the nature and quality of the intermediary’s information and on properties of the consumer’s mistakes. In particular, steering based on high-quality information about the consumer’s mistakes is typically harmful, sometimes extremely so. We argue that much real-life steering is of this type, raising the scope for a broader regulation of steering practices.
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.
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 establish convergence of beliefs and actions in a class of one-dimensional learning settings in which the agent’s model is misspecified, she chooses actions endogenously, and the actions affect how she misinterprets information. Our stochastic-approximation-based methods rely on two crucial features: that the state and action spaces are continuous, and that the agent’s posterior admits a one-dimensional summary statistic. Through a basic model with a normal–normal updating structure and a generalization in which the agent’s misinterpretation of information can depend on her current beliefs in a flexible way, we show that these features are compatible with a number of specifications of how exactly the agent updates. Applications of our framework include learning by a person who has an incorrect model of a technology she uses or is overconfident about herself, learning by a representative agent who may misunderstand macroeconomic outcomes, and learning by a firm that has an incorrect parametric model of demand.
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 explore the learning process and behavior of an individual with unrealistically high expectations (overconfidence) when outcomes also depend on an external fundamental that affects the optimal action. Moving beyond existing results in the literature, we show that the agent’s beliefs regarding the fundamental converge under weak conditions. Furthermore, we identify a broad class of situations in which “learning” about the fundamental is self-defeating: it leads the individual systematically away from the correct belief and toward lower performance. Due to his overconfidence, the agent—even if initially correct—becomes too pessimistic about the fundamental. As he adjusts his behavior in response, he lowers outcomes and hence becomes even more pessimistic about the fundamental, perpetuating the misdirected learning. The greater is the loss from choosing a suboptimal action, the further the agent’s action ends up from optimal. We partially characterize environments in which self-defeating learning occurs, and show that the decisionmaker learns to take the optimal action if, and in a sense only if, a specific non-identifiability condition is satisfied. In contrast to an overconfident agent, an underconfident agent’s misdirected learning is self-limiting and therefore not very harmful. We argue that the decision situations in question are common in economic settings, including delegation, organizational, effort, and public-policy choices.
We initiate the study of naïvete ́-based discrimination, the practice of conditioning offers on external information about consumers’ naïvete ́. Knowing that a consumer is naive increases a monopolistic or competitive firm’s willingness to generate inefficiency to exploit the consumer’s mistakes, so naïvete ́-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, naïvete ́-based discrimination lowers total welfare. In contrast, if the distortion arises only for trades with sophisticated consumers, then perfect naïvete ́-based discrimination maximizes social welfare, although imperfect discrimination often lowers welfare. If the distortion arises only for trades with naive consumers, then naïvete ́-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 naïvete ́-based discrimination to lower welfare is then weaker than prudence.
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 analyze innovation incentives when firms can invest either in increasing the product’s value (value-increasing innovation) or in increasing the hidden prices they collect from naive consumers (exploitative innovation). We show that if firms cannot return all profits from hidden prices by lowering transparent prices, innovation incentives are often stronger for exploitative than for value-increasing innovations, and are strong even for non-appropriable innovations. These results help explain why firms in the financial industry (e.g., credit-card issuers) have been willing to make innovations others could easily copy, and why these innovations often seem to have included exploitative features.
In the presence of naive consumers, a participation distortion arises in competitive markets because the additional profits from naive consumers lead competitive firms to lower transparent prices below cost. Using a simple calibration, we argue that the participation distortion in the US credit-card market may be massive. Our results call for a redirection of some of the large amount of empirical research on the quantification of the welfare losses from market power, to the quantification of welfare losses that are due to the firms’ reactions to consumer misunderstandings.
This review provides a critical survey of psychology-and-economics (“behavioral-economics”) research in contract theory. First, I introduce the theories of individual decision making most frequently used in behavioral contract theory, and formally illustrate some of their implications in contracting settings. Second, I provide a more comprehensive (but informal) survey of the psychology-and-economics work on classical contract-theoretic topics: moral hazard, screening, mechanism design, and incomplete contracts. I also summarize research on a new topic spawned by psychology and economics, exploitative contracting, that studies contracts designed primarily to take advantage of agent mistakes.
A central assumption of neoclassical economics is that reservation prices for familiar products express people’s true preferences for these products; that is, they represent the total benefit that a good confers to the consumers and are, thus, independent of actual prices in the market. Nevertheless, a vast amount of research has shown that valuations can be sensitive to other salient prices, particularly when individuals are explicitly anchored on them. In this paper, the authors extend previous research on single-price anchoring and study the sensitivity of valuations to the distribution of prices found for a product in the market. In addition, they examine its possible causes. They find that market-dependent valuations cannot be fully explained by rational inferences consumers draw about a product’s value and are unlikely to be fully explained by true market-dependent preferences. Rather, the market dependence of valuations likely reflects consumers’ focus on something other than the total benefit that the product confers to them. Furthermore, this paper shows that market-dependent valuations persist when – as in many real-life settings – individuals make repeated purchase decisions over time and infer the distribution of the product’s prices from their market experience. Finally, the authors consider the implications of their findings for marketers and consumers.
It is widely known that loss aversion leads individuals to dislike risk and, as has been argued by many researchers, in many instances this creates an incentive for firms to shield consumers and employees against economic risks. Complementing previous research, we show that consumer loss aversion can also have the opposite effect: it can lead a firm to optimally introduce risk into an otherwise deterministic environment. We consider a profit-maximizing monopolist selling to a loss-averse consumer, where (following Kőszegi and Rabin 2006) we assume that the consumer’s reference point is her recent rational expectations about the purchase. We establish that for any degree of consumer loss aversion, the monopolist’s optimal price distribution consists of low and variable “sale” prices and a high and atomic “regular” price. Realizing that she will buy at the sales prices and hence that she will purchase with positive probability, the consumer chooses to avoid the painful uncertainty in whether she will get the product by buying also at the regular price. This pricing pattern is consistent with several recently documented facts regarding retailer pricing. We show that market power is crucial for this result: when firms compete ex ante for consumers, they choose deterministic prices.
We present a generally applicable theory of focusing based on the hypothesis that a person focuses more on, and hence overweights, attributes in which her options differ more. Our model predicts that the decision maker is too prone to choose options with concentrated advantages relative to alternatives, but maximizes utility when the advantages and disadvantages of alternatives are equally concentrated. Applying our model to intertemporal choice, these results predict that a person exhibits present bias and time inconsistency when—such as in lifestyle choices and other widely invoked applications of hyperbolic discounting—the future effect of a current decision is distributed over many dates, and the effects of multiple decisions accumulate. But unlike in previous models, in our theory (1) present bias is lower when the costs of current misbehavior are less dispersed, helping explain why people respond more to monetary incentives than to health concerns in harmful consumption; and (2) time inconsistency is lower when a person commits to fewer decisions with accumulating effects in her ex ante choice. In addition, a person does not fully maximize welfare even when making decisions ex ante: (3) she commits to too much of an activity—for example, exercise or work—that is beneficial overall; and (4) makes ‘‘future-biased’’ commitments when—such as in preparing for a big event—the benefit of many periods’ effort is concentrated in a single goal.
We analyze contract choices, loan-repayment behavior, and welfare in a model of a competitive credit market when borrowers have a taste for immediate gratification. Consistent with many credit cards and subprime mortgages, for most types of nonsophisticated borrowers the baseline repayment terms are cheap, but they are also inefficiently front loaded and delays require paying large penalties. Although credit is for future consumption, nonsophisticated consumers overborrow, pay the penalties, and back load repayment, suffering large welfare losses. Prohibiting large penalties for deferring small amounts of repayment—akin to recent regulations in the US credit-card and mortgage markets—can raise welfare.
I develop a dynamic model of individual decisionmaking in which the agent derives utility from physical outcomes as well as from rational beliefs about physical outcomes (“anticipation”), and these two payoff components can interact. Beliefs and behavior are jointly determined in a personal equilibrium by the requirement that behavior given past beliefs must be consistent with those beliefs. I explore three phenomena made possible by utility from anticipation, and prove that if the decisionmaker’s behavior is distinguishable from a person’s who cares only about physical outcomes, she must exhibit at least one of these phenomena. First, the decisionmaker can be prone to self-fulfilling expectations. Second, she might be time-inconsistent even if her preferences in all periods are identical. Third, she might exhibit informational preferences, where these preferences are intimately connected to her attitudes toward disappointments. Applications of the framework to reference-dependent preferences, impulsive behaviors, and emotionally difficult choices are discussed.
We investigate costly yet futile attempts at self-control when consumption of a harmful product has a binary breakdown/no-breakdown nature and individuals tend to underestimate their need for self-control. Considering time-inconsistent preferences as well as temptation disutility, we show that becoming more sophisticated can decrease welfare and investigate what kind of mistaken beliefs lead to low welfare. With time-inconsistent preferences, being close to perfectly understanding one’s preferences but assigning zero probability to true preferences induces the worst outcome.
We develop a rational dynamic model in which people are loss averse over changes in beliefs about present and future consumption. Because changes in wealth are news about future consumption, preferences over money are reference-dependent. If news resonates more when about imminent consumption than when about future consumption, a decision maker might (to generate pleasant surprises) overconsume early relative to the optimal committed plan, increase immediate consumption following surprise wealth increases, and delay decreasing consumption following surprise losses. Since higher wealth mitigates the effect of bad news, people exhibit an unambiguous first-order precautionary-savings motive.
This article explores some conceptual issues in the study of well-being using the traditional economic approach of inferring preferences solely from choice behavior. We argue that choice behavior alone can never reveal which situations make people better off, even with unlimited data and under the maintained hypothesis of 100% rational choice. Ancillary assumptions or additional forms of data such as happiness measures are always needed. With such ancillary assumptions and additional data, however, the use of revealed preference to study well-being can be significantly improved, so that the choices people make can jointly identify preferences, mistakes, and well-being.
We modify the Salop (1979) model of price competition with differentiated products by assuming that consumers are loss averse relative to a reference point given by their recent expectations about the purchase. Consumers’ sensitivity to losses in money increases the price responsiveness of demand—and hence the intensity of competition—at higher relative to lower market prices, reducing or eliminating price variation both within and between products. When firms face common stochastic costs, in any symmetric equilibrium the markup is strictly decreasing in cost. Even when firms face different cost distributions, we identify conditions under which a focal-price equilibrium (where firms always charge the same “focal” price) exists, and conditions under which any equilibrium is focal.
We analyze ways in which heterogeneity in responsiveness to incentives (“drive”) affects employees’ incentives and firms’ incentive systems in a career concerns model. On the one hand, because more driven agents work harder in response to existing incentives than less driven ones—and therefore pay is increasing in perceived drive—there is a motive to increase effort to signal high drive. These “drive-signaling incentives” are strongest with intermediate levels of existing incentives. On the other hand, because past output of a more driven agent will seem to the principal to reflect lower ability, there is an incentive to decrease effort to signal low drive. The former effect dominates early in the career, and the latter effect dominates towards the end. To maximize incentives, the principal wants to observe a noisy measure of the agent’s effort—such as the number of hours he works—early but not late in his career.
We use Kőszegi and Rabin’s (2006) model of reference-dependent utility, and an extension of it that applies to decisions with delayed consequences, to study preferences over monetary risk. Because our theory equates the reference point with recent probabilistic beliefs about outcomes, it predicts specific ways in which the environment influences attitudes toward modest-scale risk. It replicates “classical” prospect theory—including the prediction of distaste for insuring losses—when exposure to risk is a surprise, but implies first-order risk aversion when a risk, and the possibility of insuring it, are anticipated. A prior expectation to take on risk decreases aversion to both the anticipated and additional risk. For large-scale risk, the model allows for standard “consumption utility” to dominate reference-dependent “gain-loss utility,” generating nearly identical risk aversion across situations.
We develop a model of reference-dependent preferences and loss aversion where “gain–loss utility” is derived from standard “consumption utility” and the reference point is determined endogenously by the economic environment. We assume that a person’s reference point is her rational expectations held in the recent past about outcomes, which are determined in a personal equilibrium by the requirement that they must be consistent with optimal behavior given expectations. In deterministic environments, choices maximize consumption utility, but gain–loss utility influences behavior when there is uncertainty. Applying the model to consumer behavior, we show that willingness to pay for a good is increasing in the expected probability of purchase and in the expected prices conditional on purchase. In within-day labor-supply decisions, a worker is less likely to continue work if income earned thus far is unexpectedly high, but more likely to show up as well as continue work if expected income is high.
This paper models interactions between a party with anticipatory emotions and a party who responds strategically to those emotions, a situation that is common in many health, political, employment, and personal settings. An “agent” has information with both decision-making value and emotional implications for an uninformed “principal” whose utility she wants to maximize. If she cannot directly reveal her information, to increase the principal’s anticipatory utility she distorts instrumental decisions toward the action associated with good news. But because anticipatory utility derives from beliefs about instrumental outcomes, undistorted actions would yield higher ex ante total and anticipatory utility. If the agent can certifiably convey her information, she does so for good news, but unless this leads the principal to make a very costly mistake, to shelter his feelings she pretends to be uninformed when the news is bad.
This paper models behavior when a decision maker cares about and manages her self-image. In addition to having preferences over material outcomes, the agent derives “ego utility” from positive views about her ability to do well in a skill-sensitive, “ambitious,” task. Although she uses Bayes’ rule to update beliefs, she tends to become overconfident regarding which task is appropriate for her. If tasks are equally informative about ability, her task choice is also overconfident. If the ambitious task is more informative about ability, she might initially display underconfidence in behavior, and, if she is disappointed by her performance, later become too ambitious. People with ego utility prefer to acquire free information in smaller pieces. Applications to employee motivation and other economic settings are discussed.
One of the most cogent criticisms of excise taxes is their regressivity, with lower income groups spending a much larger share of their income on goods such as cigarettes than do higher income groups. We argue that traditional quantity-based measures of incidence are only appropriate under a very restrictive ‘‘time-consistent’’ model of consumption of sin goods. A model that is much more consistent with existing evidence on smoking decisions is a time-inconsistent formulation where excise taxes on cigarettes serve a self-control function that is valued by smokers who would like to quit but cannot. This self-control function benefits lower income groups more, since they have a significantly higher price sensitivity of smoking. Calibrations show that, as a result, cigarette taxes are much less regressive than previously assumed, and are even progressive for a wide variety of parameter values.
Economic models of patient decision-making emphasize the costs of getting medical attention and the improved physical health that results from it. This note builds a model of patient decision-making when fears or anxiety about the future—captured as beliefs about next period’s state of health— also enter the patient’s utility function. Anxiety can lead the patient to avoid doctor’s visits or other easily available information about her health. However, this avoidance cannot take any form: she will never avoid the doctor with small problems, and under regularity conditions she will never go to a bad doctor to limit the information received.
Some people have self-control problems regularly. This paper adds endogenous retirement to Laibson’s quasi-hyperbolic discounting savings model [Quarterly Journal of Economics 112 (1997) 443–477]. Earlier selves think that the deciding self tends to retire too early and may save less to induce later retirement. Still earlier selves may think the pre-retirement self does this too much, saving more to induce early retirement. The consumption pattern may be different from that with exponential discounting. Other observational non-equivalence includes the impact of changing mandatory retirement rules or work incentives on savings and a possibly negative marginal propensity to consume out of increased future earnings. Naive agents are briefly considered.
This paper makes two contributions to the modeling of addiction. First, we provide new and convincing evidence that smokers are forward-looking in their smoking decisions, using state excise tax increases that have been legislatively enacted but are not yet effective, and monthly data on consumption. Second, we recognize the strong evidence that preferences with respect to smoking are time inconsistent, with individuals both not recognizing the true difficulty of quitting and searching for self-control devices to help them quit. We develop a new model of addictive behavior that takes as its starting point the standard “rational addiction” model, but incorporates time-inconsistent preferences. This model also exhibits forward-looking behavior, but it has strikingly different normative implications; in this case optimal government policy should depend not only on the externalities that smokers impose on others but also on the “internalities” imposed by smokers on themselves. We estimate that the optimal tax per pack of cigarettes should be at least one dollar higher under our formulation than in the rational addiction case.
The isothermal change of the magnetic entropy of a magnetically ordered material upon application of external magnetic field can be calculated from the temperature and field dependence of the magnetization or of the specific heat. The adiabatic temperature change, i.e., the magnetocaloric effect (MCE) can be measured directly or can be calculated via different methods using the field-dependent specific heat values, or a combination of data obtained via magnetization and thermal measurements. In the present study, magnetic and thermal measurements were carried out on Gd75Y25(TC=232K) and Gd48Y52(TC=161 K) samples, for applied fields ranging between 0 and 7 T. From both datasets, the magnetic entropy change and MCE values were calculated and compared, in order to assess the mutual reliability of the methods applied. The magnetically or thermally deduced specific heat discontinuities show a reasonable agreement within experimental error. Similar comparison of the calculated magnetic entropy changes reveals that the measured transition temperature and the shape of the curve do not depend on the method selected. It is demonstrated that the choice of an integration constant during entropy calculation has a significant impact on the adiabatic temperature change deduced from the field and temperature dependence of the entropies. For the MCE, a better approximation can be obtained using the magnetically acquired magnetic entropy change and the field-dependent specific heat. The results prove that magnetic measurements carried out in high enough magnetic fields provide reliable information on the isothermal magnetic entropy change and, when combined with field-dependent specific heat measurements, on the magnetocaloric effect as well.

other publications

This chapter surveys the literature on behavioral industrial organization, covering four broad topics: (1) how rational firms interact with consumers who make systematic mistakes in evaluating products; (2) how rational firms respond to consumer preferences that differ from those usually assumed in industrial organization; (3) how psychological phenomena affect firms' behavior; and (4) what policy insights—especially on issues in competition and consumer-protection policy—follow from the literature on behavioral industrial organization.
Heidhues, P., Kőszegi, B., & Murooka, T. (2011). Deception and Consumer Protection in Competitive Markets. Anthology on Pros and Cons of Consumer Protection, 44-76.
Kőszegi, B., & Rabin, M. (2008). Revealed Mistakes and Revealed Preferences. In A. Caplin & A. Schotter (Eds.), The Foundations of Positive and Normative Economics (193–209). Oxford University Press.
Kőszegi, B., & Rabin, M. (2007). Mistakes in Choice-Based Welfare Analysis. American Economic Review, 97(2), 477-481.
Kőszegi, B. (2005). On the Feasibility of Market Solutions to Self-Control Problems. Swedish Economic Policy Review, 12(2), 71-94.