Stefan T. Trautmann

Testosterone Inhibits Trust but Promotes Reciprocity

The steroid hormone testosterone has been associated with behavior intended to obtain or maintain high social status. Although such behavior is typically characterized as aggressive and competitive, it is clear that high social status is achieved and maintained not only through antisocial behavior but also through prosocial behavior. In the present experiment, we investigated the impact of testosterone administration on trust and reciprocity using a double-blind randomized control design. We found that a single dose of 0.5 mg of testosterone decreased trust but increased generosity when repaying trust. These findings suggest that testosterone may mediate different types of status-seeking behavior. It may increase competitive, potentially aggressive, and antisocial behavior when social challenges and threats (i.e., abuse of trust and betrayal) need to be considered; however, it may promote prosocial behavior in the absence of these threats, when high status and good reputation may be best served by prosocial behavior.

Tempus fugit : Time pressure in risky decisions

We study the effects of time pressure on risky decisions for pure gain prospects, pure loss prospects, and mixed prospects involving both gains and losses. In an experiment we find that risk aversion for gains is robust under time pressure whereas risk seeking for losses turns into risk aversion under time pressure. For mixed prospects, subjects become more loss averse and more gain seeking under time pressure, depending on the framing of the prospects. The results suggest the importance of aspiration levels under time pressure. We discuss the implications of our findings for decision making situations that involve time pressure.

Belief Elicitation: A Horse Race Among Truth Serums

In survey studies, probabilistic expectations about uncertain events are typically elicited by asking respondents for their introspective beliefs. If more complex procedures are feasible, beliefs can be elicited by incentive compatible revealed preference mechanisms (“truth serums”). Various mechanisms have been proposed in the literature, which differ in the degree to which they account for respondents’ deviations from expected value maximization. In this paper, we pit non-incentivized introspection against five truth serums, to elicit beliefs in a simple two-player game. We test the internal validity (additivity and predictive power for own behavior), and the external validity (predictive power for other players’ behavior, or accuracy) of each method. We find no differences among the truth serums. Beliefs from incentivized methods are better predictors of subjects’ own behavior compared to introspection. However, introspection performs equally well as the truth serums in terms of accuracy and additivity.

Preference Reversals for Ambiguity Aversion

This paper finds preference reversals in measurements of ambiguity aversion, even if psychological and informational circumstances are kept constant. The reversals are of a fundamentally different nature than the reversals found before because they cannot be explained by context-dependent weightings of attributes. We offer an explanation based on Sugdens random-reference theory, with different elicitation methods generating different random reference points. Then measurements of ambiguity aversion that use willingness to pay are confounded by loss aversion and hence overestimate ambiguity aversion. This paper was accepted by Teck Ho, decision analysis.

Social Class and (Un)Ethical Behavior: A Framework, With Evidence From a Large Population Sample

Differences in ethical behavior between members of the upper and lower classes have been at the center of civic debates in recent years. In this article, we present a framework for understanding how class affects ethical standards and behaviors. We apply the framework using data from a large Dutch population sample. The data include objective measures of class, survey responses relating to ethical behavior, and results from an experiment designed to probe ethical choices. Ethical behavior proves to be affected by (a) moral values, (b) social orientation, and (c) the costs and benefits of taking various actions. Strong class differences emerge in each of these areas, leading to differences in behavior. Moreover, strong differences among different conceptions of class (wealth, education, etc.) produce additional variation. We argue that the relationship between class and ethical behavior is far from a simple pattern; it is a complex mosaic.

Strategic Loan Defaults and Coordination: An Experimental Analysis

This paper experimentally studies the impact of uncertainty about bank and borrower fundamentals on loan repayment. We find that solvent borrowers are more likely to default strategically when stricter disclosure creates common knowledge about bank weakness. Borrowers are also less likely to repay in the presence of higher uncertainty regarding other. Borrowers’ financial health, regardless of disclosure rules. We show that uncertainty about fundamentals changes the risk dominance properties of the coordination problem, and that these changes subsequently explain borrowers’ default. For the individual borrower, loss aversion and negative past experiences reduce repayment, suggesting that bank failure can be contagious in times of distress.

Selection into Auctions for Risky and Ambiguous Prospects

We study experimentally the selection into first-price sealed-bid auctions for a risky or an ambiguous prospect. Most subjects chose to submit a bid for the risky prospect, leading to thinner markets for the ambiguous prospect. Transaction prices for both prospects were equal although subjects expected the ambiguous markets to be smaller. Evidence of a positive correlation between risk and ambiguity aversion suggests that the ambiguous markets were populated by relatively risk tolerant bidders. A control experiment with selection in a simple choice task shows that subjects correctly anticipate the effects of selection on market size and risk attitudes.

Understanding Bank-Run Contagion

We study experimental coordination games to examine through which transmission channels, and under which information conditions, a panic-based depositor-run at one bank may trigger a panic-based depositor-run at another bank. We find that withdrawals at one bank trigger withdrawals at another bank by increasing players JEL Classification: D81, G21, G28

Shunning uncertainty: The neglect of learning opportunities

Financial, managerial, and medical decisions often involve alternatives whose possible outcomes have uncertain probabilities. In contrast to alternatives whose probabilities are known, these uncertain alternatives offer the benefits of learning. In repeat-choice situations, such learning brings value. If probabilities appear favorable (unfavorable), a choice can be repeated (avoided). In a series of experiments involving bets on the colors of poker chips drawn from bags, decision makers often prove to be blind to the learning opportunities offered by uncertain probabilities. They forgo significant expected payoffs when they shun uncertain alternatives in favor of known ones. Worse, when information is revealed, many make choices contrary to learning. Priming with optimal strategies offers little improvement. Such decision makers violate identified requirements for making rational decisions.

Prospect theory or construal level theory? Diminishing sensitivity vs. psychological distance in risky decisions.

Attitudes toward risks are central to organizational decisions. These attitudes are commonly modeled by prospect theory. Construal level theory has been proposed as an alternative theory of risky choice, accounting for psychological distance deriving from temporal, spatial and social aspects of risk that are typical of agency situations. Unnoticed in the literature, the two theories make contradicting predictions. The current study investigates which theory provides a better description of risky decisions in the presence of temporal, spatial, and social factors. We find that the psychophysical effects modeled by prospect theory dominate the psychological distance effects of construal level theory.