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Humans frequently cooperate to achieve benefits unattainable through selfish behaviour. Punishment of free-riders is key for sustaining cooperation but also costly, raising questions about the origins of such behaviour. Some evolutionary models suggest that individuals may be willing to hurt unknown others in competitive environments. However, empirical evidence about the effect of the scale of competition on strategies involving hurtful behaviour in human groups, such as spite, retaliation for hurting, and punishment of free-riders, is missing. Using a laboratory experiment, we manipulate the scale of competition to investigate its influence on hurtful and helpful behaviours, between unknown humans in an indirect reciprocity game. We observe distinct behavioural patterns between local and global competition. When competition is local and thus confined to take place within isolated groups we find frequent hurting as an expression of spite and retaliation. In contrast, when competition extends globally across several groups, hurting is used primarily for punishment of free-riders whereas helping behaviour is rewarded, which together promotes cooperation. Thus, while isolated competition fosters inefficient, antisocial behaviour, global competition encourages prosociality and cooperation.

This paper experimentally investigates the relationship between an investor and a project manager. Project managers choose from a pool of projects, the success probabilities of which are uncertain. Information about the future success probability of a project is gained by observing its outcome. Investors can change projects, but also have to change project managers if they want to do so. An additional joint project or a voluntary transfer precedes their interaction. We hypothesize that investors favor projects that are managed by project managers with whom they have shared positive experiences in the past, even though these past experiences do not provide any information about a project's success probability. The role of this social element is isolated using a control treatment in which the role of the project manager does not exist. Interaction through a voluntary transfer plays a clear and significant role in the investors' decision making via bonding, whereas the influence of merely sharing a positive or negative experience proves more complex.

For reward-based crowdfunding, we introduce the strategy-proof Generalized Moulin-Shenker mechanism (GMS) and compare its performance to the prevailing All-Or-Nothing mechanism (AON). Theoretically, GMS outperforms AON in equilibrium profit and funding success. We test these predictions experimentally, distinguishing between a sealed-bid and a dynamic version of GMS. We find that the dynamic GMS outperforms the sealed-bid GMS. It performs better than AON when the producer aims at maximizing funding success. For crowdfunding in practice, this suggests that the current standard of financing projects may be improved upon by implementing a crowdfunding mechanism that is similar to the dynamic GMS.

Information about the consequences of our consumption choices can be unwelcome, and people sometimes avoid it. We investigate a situation where one person possesses information that is inconvenient for another, and study why and when they decide to transmit that information. We introduce a simple and portable experimental game to analyze transmission of inconvenient information. In this game, a Sender can inform a Receiver at a small cost about a negative externality associated with a tempting and profitable action for the Receiver. The results from our online experiment (N = 1,512) show that Senders transmit more information for large negative externalities. Sender's decisions are largely driven by their own preferences for information. However, some Senders take the Receiver's feelings into account, by transmitting evidence of positive externalities or by suppressing negative information upon the Receiver's request. Understanding the decision to share inconvenient information matters, as it will affect the personal and political will to address important externalities and can inform strategies to encourage the transmission of inconvenient information within organizations.

Reorientation of attention to threatening stimuli is a fundamental part of human cognition. Such interaction between cogni-tive and affective processes is often associated with faster response times. In the present study, the role of the right angular gyrus (AG) in reorienting to threat is examined. An exogenous spatial cueing paradigm was adopted with threatening and nonthreatening targets. Threat was induced by means of differential fear conditioning of the target. Single pulse transcranial magnetic stimulation (TMS) was applied to the right AG at different stimulus onset asynchronies (SOA) after target onset (range 30–300 ms). Transcranial magnetic stimulation was predicted to interfere at an earlier SOA with reorienting (during invalidly cued trials) to threatening targets. Even though an overall decrement in performance to targets contralateral to TMS stimulation was found, TMS to right AG did not specifically affect reorienting, neither to safe nor to threatening targets. We suggest that detection of biologically significant stimuli outside the focus of attention may depend more on the ventral frontoparietal rather than dorsal frontoparietal network of attention.