We investigate several possible links between psychological factors and trading performance in a sample of 80 anonymous day-traders. Using daily emotional-state surveys over a fiveweek period as well as personality inventory surveys, we construct measures of personality traits and emotional states for each subject and correlate these measures with daily normalized profits-and-losses records. We find that subjects whose emotional reaction to monetary gains and losses was more intense on both the positive and negative side exhibited significantly worse trading performance. Psychological traits derived from a standardized personality inventory survey do not reveal any specific “trader personality profile”, raising the possibility that trading skills may not necessarily be innate, and that different personality types may be able to perform trading functions equally well after proper instruction and practice.

The battle between proponents of the Efficient Markets Hypothesis and champions of behavioral finance has never been more pitched, and little consensus exists as to which side is winning or the implications for investment management and consulting. In this article, I review the case for and against the Efficient Markets Hypothesis and describe a new framework—the Adaptive Markets Hypothesis—in which the traditional models of modern financial economics can coexist alongside behavioral models in an intellectually consistent manner. Based on evolutionary principles, the Adaptive Markets Hypothesis implies that the degree of market efficiency is related to environmental factors characterizing market ecology such as the number of competitors in the market, the magnitude of profit opportunities available, and the adaptability of the market participants. Many of the examples that behavioralists cite as violations of rationality that are inconsistent with market efficiency—loss aversion, overconfidence, overreaction, mental accounting, and other behavioral biases—are, in fact, consistent with an evolutionary model of individuals adapting to a changing environment via simple heuristics. Despite the qualitative nature of this new paradigm, I show that the Adaptive Markets Hypothesis yields a number of surprisingly concrete applications for both investment managers and consultants.

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Neuroeconomics merges methods from neuroscience and economics to better understand how the human brain generates decisions in economic and social contexts. Neuroeconomics is part of the general quest for microfoundations—in this case, the microfoundation of individual decision-making in social contexts. The economic model of individual decision-making is based on three concepts: the action set, preferences, and beliefs. Economists assume that an individual will choose his preferred action for a given set of available actions and a given belief about the states of the world and the other players ’ actions. Neuroeconomics provides a microfoundation for individual beliefs, preferences, and behavior; it does so by examining the brain processes associated with the formation of beliefs, the perception of the action set, and the actual choice. Moreover, since the set of available actions can be framed in different ways and different frames of the same action set sometimes elicit different behaviors, neuroeconomics may also contribute to a deeper understanding of framing effects. This paper discusses recent neuroeconomic evidence related to other-regarding (nonselfish) behaviors and the decision to trust in other people’s nonselfish behavior. As we will show, this evidence supports the view that people derive nonpecuniary utility (i) from mutual cooperation in social dilemma (SD) games and (ii) from punishing unfair behavior in these games. Thus, mutual cooperation that takes place despite strong free-riding incentives, and the punishment of free riders in SD games is not irrational, but better understood as rational behavior of people with corresponding social preferences. Finally, we report the results of a recent study that examines the impact of the neuropeptide oxytocin (OT) on trusting and trustworthy behavior in a sequential SD. Animal studies have identified OT as a hormone that induces

Abstract: The subjective expected utility (SEU) model rests on very strong assumptions about the consistency of decision making across a wide range of situations. The descriptive validity of these assumptions has been extensively challenged by behavioral psychologists during the last few decades, and the normative validity of the assumptions has also been reappraised by many statisticians, philosophers, and economists, motivating the development of more general utility theories and decision models. These generalized models are characterized by features such as imprecise probabilities, nonlinearly weighted probabilities, source-dependent risk attitudes, and state-dependent utilities, permitting the pattern of the decision maker’s behavior to change with the decision context and to perhaps satisfy the usual SEU assumptions only locally. Recent research in the emerging field of neuroeconomics sheds light on the physiological basis of decision making, the nature of preferences and beliefs, and interpersonal differences in decision competence. These findings do not necessarily invalidate the use of SEU-based decision analysis tools, but they suggest that care needs to be taken to structure preferences and to assess beliefs and risk attitudes in a manner that is appropriate for the decision and also for the decision maker. Key words: subjective probability, expected utility, non-expected utility, Savage's axioms, surething

Abstract. Understanding more about how the brain functions should help us understand economic behaviour. But some would have us believe that it has done this already, and that insights from neuroscience have already provided insights in economics that we would not otherwise have. Much of this is just academic marketing hype, and to get down to substantive issues we need to identify that fluff for what it is. After we clear away the distractions, what is left? The answer is that a lot is left, but it is still all potential. That is not a bad thing, or a reason to stop the effort, but it does point to the need for a serious reconsideration of what neuroeconomics is and what passes for explanation in this literature. I argue that neuroeconomics can be a valuable field, but not the way it is being developed and “sold ” now. The same is true more generally of behavioural economics, which shares

Privacy decision making can be surprising or even appear contradictory: we feel entitled to protection of information about ourselves that we do not control, yet willingly trade away the same information for small rewards; we worry about privacy invasions of little significance, yet overlook those that may cause significant damages. Dichotomies between attitudes and behaviors, inconsistencies in discounting future costs or rewards, and other systematic behavioral biases have long been studied in the psychology and behavioral economics literatures. In this paper we draw from those literatures to discuss the role of uncertainty, ambiguity, and behavioral biases in privacy decision making.

I construct a model in which an oligopoly first invests in persuasive advertising in order to induce brand loyalty to consumers who would otherwise buy the cheapest alternative on the market, and then competes in prices. Despite ex-ante symmetry, at equilibrium, there is one firm which chooses a lower advertising level, while the remaining ones choose the same higher advertising. For the endogenous profile of advertising expenditure, there are a family of pricing equilibria with at least two firms randomizing on prices. The setting offers a way of modelling homogenous product markets where persuasive advertising creates subjective product differentiation and changes the nature of subsequent price competition. The pricing stage of the model can be regarded as a variant of the Model of Sales by Varian (1980) and the two stage game as a way to endogenize consumers heterogeneity raising a robustness question to Varian’s symmetric setting.

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