The Interaction of Legal and Social Norm Enforcement

Although legal sanctions are often non-deterrent, we frequently observe compliance with ‘mild laws’. A possible explanation is that the incentives to comply are shaped not only by legal, but also by social sanctions. This paper employs a novel experimental approach to study the link between legal and social norm enforcement. We analyze whether the two institutions are complements or substitutes. Our results show that legal sanctions partially crowd out social norm enforcement. The welfare effect from mild laws is positive, however, as a higher level of compliance is achieved at lower enforcement costs.social sanctions, legal sanctions, norm enforcement, mild laws, laboratory experiment, VCM, public goods

Choosing your object of benevolence: a field experiment on donation options

In a large natural field experiment, we explore the effect of providing donors with the opportunity to choose the target country for their donations. We find that only a small fraction of donors use the option, which might reflect a reluctance to consider tradeoffs when those concern important, 'protected', values. However, those donors who choose their object of benevolence give significantly more, even when controlling for their donation history. In view of the latest research on identifable-victim effects, our findings underline that less inclusive targets can evoke more intense feelings than more inclusive ones stressing that altruistic motivation seems to be mediated by aroused empathetic emotions. --charitable giving,identifiable victim,field experiment,altruism,contingent valuation

Can we manage first impressions in cooperation problems? An experiment

We study how cooperative behavior reacts to selective (favorable or unfavorable) pre-play information about the cooperativeness of other, unrelated groups within an experimental framework that is sufficiently rich for conflicting behavioral norms to emerge. We find that cooperation crucially depends on pre-play information, coinciding with a change in initial beliefs. Over time, behavior within both types of groups becomes increasingly homogeneous, indicating the formation of two rather different social norms, depending on whether pre-play information was favorable or unfavorable. In addition, we find unfavorable information to substantially reduce the effectiveness of peer punishment. For these differences to emerge it is immaterial whether each member or only one member of a four-person group receives the pre-play information.experiment, information, Norms, cooperation, Effectiveness of Sanctions, Expectations

Nominalist Heuristics and Economic Theory

This paper introduces a new theoretic entity, a nominalist heuristic, defined as a focus on prominent numbers, indices or ratios. Abstractions used in the evaluation stage of decision making typically involve nominalist heuristics that are incompatible with expected utility theory which excludes the evaluation stage, and are also incompatible with prospect theory which assumes that, while the evaluation procedure can involve systematic mistakes, the overall decision situation is nevertheless sufficiently simple: 1) for economists and psychologists to identify what is a mistake, and 2) to be compatible with maximisation. But in the typical complex situation giving rise to nominalist heuristics neither 1) nor 2) hold, and therefore what is required is a fundamentally different class of models that allow for the progressive anticipated changes in knowledge ahead faced under risk and uncertainty, namely models under the umbrella of SKAT, the Stages of Knowledge Ahead Theory. A sequel paper. Pope et al 2009b, shows field and laboratory evidence of heuristics in the form of prominent numbers entering exchange rate determination.nominalism, money illusion, heuristic, unpredictability, experiment, SKAT the Stages of Knowledge Ahead Theory, prominent numbers, prominent indices, prominent ratios, equality, historical benchmarks, complexity, decision costs, evaluation

Structure of the Vibrio cholerae Type VI secretion tubule at sub-nanometer resolution

The bacterial type VI secretion system is a multicomponent molecular machine directed against eukaryotic host cells and competing bacteria. It consists of a contractile tubule that is attached to a membrane protein complex. Upon tubule contraction, a needle is ejected into target cells to translocate toxic effectors into the cell. Due to structural and functional homologies of several proteins of the secretion system to proteins of contractile bacteriophage tails, the system is generally described as an inverted phage tail. Following this analogy, the secretion process is driven by energy stored in the elongated conformation of the Type VI secretion tubule for which also partial structural homology to bacteriophage tail sheath proteins has been predicted. However, this prediction has not been corroborated by structural data so far. The AAA+ ATPase ClpV plays an important role in the secretion process, as it disassembles the contracted tubule, putatively for recycling of the complex. Even though the binding site for ClpV has been identified in VipB, the molecular mechanism which recruits the ATPase specifically to the contracted tubule is not known yet. In a collaborative project with PD Dr. Axel Mogk and colleagues at the DKFZ Heidelberg and the group of Dr. Franz Herzog at the Gene Center Munich, we investigate the structure of the Vibrio cholerae Type VI secretion tubule consisting of the proteins VipA and VipB. We employ a hybrid methods approach of cryo electron microscopic 3D reconstruction and electron microscopic and biochemical labeling techniques supported by cross-linking mass spectrometry to develop a structural model of VipA and VipB in the tubule. We are able to resolve the three-dimensional structure of the helical VipA/B tubule up to 6 Å which allows us to locate secondary structure elements. We describe the arrangement of VipA and VipB in the asymmetric unit and show that the architecture of the tubule is mainly defined by contacts between C-terminal domains of VipB which are structurally similar to domain IV of viral tail sheath proteins. By comparison to the T4 bacteriophage tail sheath, we suggest that these structurally homologous parts mediate the common function of contraction. Additionally, the VipA/B tubule has been adapted towards efficient recycling of contracted Type VI secretion systems. VipB is equipped with a specific four-helix bundle N-terminal domain which carries the ClpV binding motif. Also for VipA, no correspondency to any other known structural part of a phage-like contractile system is found. We propose that it serves as a chaperone for VipB. Based on the observed structural homologies between the T4 phage tail sheath protein and VipB, we model the elongated state of the VipA/B tubule using known low resolution structures of the elongated T4 phage tail. Furthermore, we suggest a molecular mechanism for Type VI secretion tubule recycling. In the elongated state of the tubule, the VipB N-terminal domain is hidden in the tubule wall, making the ClpV binding motif inaccessible for the ATPase. Therefore, ClpV-mediated recycling of the tubule is restricted to its contracted state.Das bakterielle Typ-VI-Sekretionssystem ist eine aus vielen unterschiedlichen Teilen bestehende molekulare Maschine, die gegen eukaryotische Wirtszellen und konkurrierende Bakterien gerichtet ist. Sie besteht aus einem kontraktionsfähigen Tubulus, welcher mit einem Komplex aus Membranproteinen verbunden ist. Durch Kontraktion des Tubulus wird eine Nadel in eine Zielzelle gestoßen, um Gifte in die Zelle zu injizieren. Aufgrund von strukturellen und funktionalen Homologien von einigen Proteinen des Sekretionssystems zu Proteinen des kontraktionsfähigen Bakteriophagenschwanzes wird das System allgemein als umgedrehter Phagenschwanz beschrieben. In dieser Analogie wird der Sekretionsprozess durch die in der elongierten Konformation des Typ-VI-Sekretionstubulus gespeicherte Energie angetrieben. Für ihn wurde auch eine teilweise strukturelle Homologie zum Mantelprotein des Bakteriophagenschwanzes vorhergesagt, aber nie durch strukturelle Daten belegt. Die AAA+ ATPase ClpV spielt eine wichtige Rolle im Sekretionsprozess, da sie den kontrahierten Tubulus zerlegt, vermutlich zur Wiederverwertung des Komplexes. Obwohl die ClpV-Bindestelle in VipB bereits identifiziert wurde, ist der molekulare Mechanismus, der die ATPase ausschließlich an kontrahierten Tubuli binden lässt, unbekannt. In einem Kollaborationsprojekt mit PD Dr. Axel Mogk und Mitarbeitern am DKFZ Heidelberg und der Gruppe von Dr. Franz Herzog am Gen-Zentrum München, untersuchen wir die Struktur des Typ-VI-Sekretionstubulus aus Vibrio cholerae, welcher aus den Proteinen VipA und VipB besteht. Wir verbinden in unserem Ansatz die 3D-Rekonstruktion aus kryo-elektronenmikroskopischen Bildern mit elektronenmikroskopischen und biochemischen Markierungsmethoden und entwickeln ein Strukturmodell von VipA und VipB im Tubulus, welches durch den massenspektrometrischen Nachweis chemisch quervernetzter Peptide gestützt wird. Wir können die dreidimensionale Struktur des helikalen VipA/B-Tubulus bis auf 6 Å auflösen, was es uns ermöglicht, Sekundärstrukturelemente zu lokalisieren. Wir beschreiben die Anordnung von VipA und VipB in der asymmetrischen Untereinheit und zeigen, dass die Architektur des Tubulus hauptsächlich durch Kontakte zwischen C-terminalen Domänen von VipB bestimmt wird, welche strukturell der Domäne IV der Mantelproteine des Bakteriophagenschwanzes ähneln. Der Vergleich mit dem Mantel des T4 Bakteriophagenschwanzes, führt uns zu dem Vorschlag, dass diese struktur-homologen Bestandteile die gleiche Funktion in der Kontraktion besitzen. Zusätzlich ist der VipA/B-Tubulus einer effizienten Wiederverwertung des Typ-VI-Sekretionssystems angepasst. VipB besitzt eine spezielle N-terminale Domäne, die aus einem Bündel aus vier Helices besteht und das Erkennungsmotiv für ClpV trägt. Für VipA finden wir ebenfalls keine Entsprechung zu anderen phagen-ähnlichen kontraktionsfähigen Systemen. Unserer Ansicht nach dient es als Chaperon für VipB. Basierend auf den beobachteten Strukturhomologien zwischen dem Mantelprotein des T4 Bakteriophagenschwanzes und VipB, entwerfen wir unter der Verwendung von niedrig aufgelösten Strukturen des elongierten T4 Phagenschwanzes ein Modell des elongierten Zustands des VipA/B-Tubulus. Des Weiteren schlagen wir einen molekularen Mechanismus für die Wiederverwertung des Typ-VI-Sekretionstubulus vor. Im elongierten Zustand des Tubulus ist die N-terminale Domäne von VipB in der Wand des Tubulus versteckt. Daher ist das ClpV-Erkennungsmotiv für die ATPase nicht zugänglich und der Abbau des Tubulus durch ClpV auf seinen kontrahierten Zustand beschränkt

Equity and Efficiency in Multi-Worker Firms: Insights from Experimental Economics

In this paper, we discuss recent evidence from economic experiments that study the impact of social preferences on workplace behavior. We focus on situations in which a single employer interacts with multiple employees. Traditionally, equity and efficiency have been seen as opposing aims in such work environments: individual pay-for-performance schemes maximize efficiency but might lead to inequitable outcomes. We present findings from laboratory experiments that show under which circumstances partially incomplete contracts can create equitable work environments while at the same time reaching surprisingly efficient outcomes.laboratory experiments, wage setting, equity, gift exchange, reciprocity, incomplete contracts, incentives, organizational economics

The currency of reciprocity - gift-exchange in the workplace

What determines reciprocity in employment relations? We conducted a controlled field experiment to measure the extent to which monetary and non-monetary gifts affect workers' performance. We find that nonmonetary gifts have a much stronger impact than monetary gifts of equivalent value. We also observe that when workers are offered the choice, they prefer receiving the money but reciprocate as if they received a nonmonetary gift. This result is consistent with the common saying, 'it's the thought that counts.' We underline this point by showing that also monetary gifts can effectively trigger reciprocity if the employer invests more time and effort into the gift's presentation. --field experiment,reciprocity,gift exchange,non-monetary gifts,in-kind gifts

Putting Reciprocity to Work - Positive versus Negative Responses in the Field

We study the role of reciprocity in a labor market field experiment. In a recent paper, Gneezy and List (2006) investigate the impact of gift exchange in this context and find that it has only a transient effect on long run outcomes. Extending their work to examine both positive and negative reciprocity, we find consonant evidence in the positive reciprocity condition: the gift does not work well in the long run (if at all). Yet, in the negative reciprocity treatment we observe much stronger effects: a wage reduction has a significant and lasting negative impact on efforts. Together, these results highlight the asymmetry of positive and negative reciprocity that exists in the field, and provide an indication of the relative importance of each in the long run.reciprocity, gift exchange, field experiment

Choosing your object of benevolence : a field experiment on donation options

In a large natural field experiment, we explore the effect of providing donors with the opportunity to choose the target country for their donations. We find that only a small fraction of donors use the option, which might reflect a reluctance to consider tradeoffs when those concern important, 'protected', values. However, those donors who choose their object of benevolence give significantly more, even when controlling for their donation history. In view of the latest research on identifiable-victim effects, our findings underline that less inclusive targets can evoke more intense feelings than more inclusive ones - stressing that altruistic motivation seems to be mediated by aroused empathetic emotions

Gift Exchange and Workers' Fairness Concerns: When Equality Is Unfair

We study how different payment modes influence the effectiveness of gift exchange as a contract enforcement device. In particular, we analyze how horizontal fairness concerns affect performance and efficiency in an environment characterized by contractual incompleteness. In our experiment, one principal is matched with two agents. The principal pays equal wages in one treatment and can set individual wages in the other. We find that the use of equal wages elicits substantially lower efforts. This is not caused by monetary incentives per se since under both wage schemes it is profit-maximizing for agents to exert high efforts. The treatment difference instead seems to be driven by the fact that the norm of equity is violated far more frequently in the equal wage treatment. After having suffered from violations of the equity principle, agents withdraw effort. These findings hold even after controlling for the role of intentions, as we show in a third treatment. Our results suggest that adherence to the norm of equity is a necessary prerequisite for successful establishment of gift-exchange relations.reciprocity, gift exchange, equity, wage equality, wage setting, incomplete contracts