Working Papers

Intertemporal Prospect Theory Paper (PDF)
Immanuel Lampe and Matthias Weber

Note: We received the Vernon Smith Young Talent Award for this paper from the Society for Experimental Finance.

Prospect Theory is the most prominent contender of expected utility theory to describe decisions under risk. In atemporal contexts, prospect theory is well understood. In intertemporal contexts, however, it is not clear how prospect theory should be applied (in particular, whether probabilities should be weighted within time periods or whether the probabilities of present values should be weighted). It is also unclear what parametric specifications of probability-weighting and value functions should be used. We find in a pre-registered experiment on a representative sample that an application of prospect theory weighting probabilities of present values predicts decisions best. Estimated probability weighting functions are very similar to those typically estimated in atemporal settings, while value functions are almost linear with a loss aversion coefficient close to one.

Nudging Civilian Evacuation During War: Evidence from Ukraine Paper (PDF)
Seung-Keun Martinez, Monika Pompeo, Roman Sheremeta, Volodymyr Vakhitov, Matthias Weber, and Nataliia Zaika

In the media: Vox Ukraine, HSG Newsroom (German version).

In times of war, evacuating civilians from conflict zones is of critical importance for their survival and well-being. However, many people are hesitant to evacuate. Text-based nudges are a promising, yet unexplored, venue to increase the willingness to evacuate. We conduct a controlled survey experiment in Ukraine, manipulating the framing of automated alert messages. Our findings suggest that providing individuals with an evacuation plan by the authorities is crucial. The specific framing of the message itself does not seem to play a role in the perceived effectiveness of the messages. Heterogeneity analysis shows that women respond more strongly to information about a provided evacuation plan. Furthermore, having a pre-existing personal evacuation plan and being provided with one by the authorities act as substitutes.

The Role of the End Time in Experimental Asset Markets Link to paper
Anita Kopányi-Peuker and Matthias Weber

By now there are hundreds of scientific articles on experimental asset markets. Almost all of these experiments use a short and definite horizon. This may be one of the starkest differences to financial asset markets outside the laboratory, which usually have indefinite and comparatively long horizons. We analyze the role of the end time in an asset market experiment in which we vary the length of the horizon and whether the end time is definite or indefinite. We find recurring bubbles and similar price dynamics in all treatments (with moderately lower prices in the treatments with a long horizon).

Fake News in Social Networks Link to paper
Christoph Aymanns, Jakob Foerster, Co-Pierre Georg, and Matthias Weber

We propose multi-agent reinforcement learning as a new method for modeling fake news in social networks. This method allows us to model human behavior in social networks both in unaccustomed populations and in populations that have adapted to the presence of fake news. In particular the latter is challenging for existing methods. We find that a fake-news attack is more effective if it targets highly connected people and people with weaker private information. Attacks are more effective when the disinformation is spread across several agents than when the disinformation is concentrated with more intensity on fewer agents. Furthermore, fake news spread less well in balanced networks than in clustered networks. We test a part of these findings in a human-subject experiment. The experimental evidence provides support for the predictions from the model. This suggests that our model is suitable to analyze the spread of fake news in social networks.

Credit Default Swap Regulation in Experimental Bond Markets Paper (PDF)
Matthias Weber, John Duffy, and Arthur Schram

Credit default swaps (CDS) played an important role in the financial crisis of 2008. While CDS can be used to hedge risks, they can also be used for speculative purposes (as occurred during the financial crisis) and regulations have been proposed to limit such speculative use. Here, we provide the first controlled experiment analyzing the pricing of credit default swaps in a bond market subject to default risk. We further use the laboratory as a test bed to analyze CDS regulation. Our results show that the regulation achieves the goal of increasing the use of CDS for hedging purposes while reducing the use of CDS for speculation. This success does not come at the expense of lower bond IPO revenues and does not negatively affect CDS prices or bond prices in the secondary market.