This paper investigates whether and to what extent group identity plays a role in peer effects on risk behaviour. We run a laboratory experiment in which different levels of group identity are induced through different matching protocols (random or based on individual painting preferences) and the possibility to interact with group members via an online chat in a group task. Risk behaviour is measured by using the Bomb Risk Elicitation Task and peer influence is introduced by giving subjects feedback regarding group members’ previous decisions. We find that subjects are affected by their peers when taking decisions and that group identity influences the magnitude of peer effects: painting preferences matching significantly reduces the heterogeneity in risk behaviour compared with random matching. On the other hand, introducing a group task has no significant effect on behaviour, possibly because interaction does not always contribute to enhancing group identity. Finally, relative riskiness within the group matters and individuals whose peers are riskier than they are take on average riskier decisions, even when controlling for regression to the mean.

Charitable donations provide positive externalities and can potentially be increased with an understanding of donor preferences. We obtain a uniquely comprehensive characterization of donation motives using an experiment that varies treatments between and within subjects. Donations are increasing in peers’ donations and past subjects’ donations. These and other results suggest a model of heterogeneous beliefs about the social norm for giving. Estimation of such a model reveals substantial heterogeneity in subjects’ beliefs about and adherence to the norm. A simple fundraising strategy increases donations by an estimated 30% by exploiting previously unstudied correlations between dimensions of donor preferences.

We conduct a large scale experiment to investigate peer effects in computer assisted learning (CAL). Identification relies on three levels of randomization. We find an average 0.17 standard deviation improvement in math scores among primary school students. This average effect is the same for students treated individually or in pairs, implying that peer effects double the learning benefit from a given equipment. Among paired students, poor performers benefit more from CAL when paired with good performers and vice versa. Average performers benefit equally irrespective of who they are paired with. This suggests that the treatment is dominated by knowledge exchange between peers. We also find that CAL treatment reduces the dispersion in math scores and that the beneficial effects of CAL can be strengthened if weak students are systematically paired with strong students.

In this paper we explore the micro-level determinants of conformity. Members of the social networking service Facebook express positive support to content on the website by clicking a Like button. We set up a natural field experiment to test whether users are more prone to support content if someone else has done so before. To find out to what extent conformity depends on group size and social ties we use three different treatment conditions: (1) one stranger has Liked the content, (2) three strangers have Liked the content, and (3) a friend has Liked the content. The results show that one Like from a single stranger had no impact. However, increasing the size of the influencing group doubled the probability that subjects expressed positive support. Friendship ties were also decisive. People were, on average, four times more likely to press the Like button if a friend, rather than a stranger, had done so before them. The existence of threshold effects in our experiment clearly shows that both group size and social proximity matters when opinions are shaped.

We run an experiment to test for peer effects between teams. The subjects perform a team-work task in pairs of payoff-independent teams. They receive feedback about the outcome of their own and the paired team. Consistent with peer effects, we find that this feedback induces substantial correlation of effort choices between teams. The correlation translates into the variation of outcomes within and across pairs of teams.

Expert and peer reviews and popularity are freely available both on the Internet and in printed materials for a variety of food products. Using two experimental studies with non-hypothetical tastings and auctions, we explore the impact of peer tasting popularity, actual peer ratings, and expert ratings on demand for wines consumers can or have tasted. We find that higher own wine ratings are associated with higher willingness to pay (WTP). Morevoer, higher peer and expert rating scores increase consumer WTP for wine even after controlling for the impact of consumers’ own ratings. Observed peer popularity also increases WTP for preferred wines.

Linguistic input in multi-lingual/-cultural contexts is highly variable. We examined the production of English and Malay laterals by fourteen early bilingual preschoolers in Singapore who were exposed to several allophones of coda laterals: Malay caregivers use predominantly clear-l in English and Malay, but their English coda laterals can also be l-less (vocalised/deleted) and in formal contexts, velarised. Contrastingly, the English coda laterals of the Chinese majority are typically l-less. Findings show that English coda laterals were overall more likely to be l-less than Malay laterals like their caregivers’, but English coda laterals produced by children with close Chinese peer(s) were more likely to be l-less than those without. All children produced English coda clear-l, demonstrating the transmission of an ethnic marker that had emerged from long-term contact. In diverse settings, variation is intrinsic to the acquisition process, and input properties and language experience are important considerations in predicting language outcomes.

This study uses location-specific data to investigate the role of spatially mediated peer effects in farmers’ adoption of conservation agriculture practices. The literature has shown that farmers trust other farmers and one way to increase conservation practice adoption is through identifying feasible conservation practices in neighboring fields. Estimating this effect can help improve our understanding of what influences the adoption and could play a role in improving federal and local conservation program design. The study finds that although spatial peer effects are important in the adoption of conservation tillage and diverse crop rotation, the scale of peer effects are not substantial.

A major challenge in addressing the loss of benefits and services provided by the natural environment is that it can be difficult to find ways for those who benefit from them to pay for their preservation. We examine one such context in Malawi, where erosion from soils disturbed by agriculture affects not only farmers’ incomes, but also damages aquatic habitat and inhibits the storage and hydropower potential of dams downstream. We demonstrate that payments from hydropower producers to farmers to maintain land cover and prevent erosion can have benefits for all parties involved.

Support for organic farming is a key strategy of rural development policies in several countries. This paper studied the spatial pattern of participation in agro-environmnetal policy the policies designing to foster diffusion of organic farming. The ultimate goal is to investigate the impact of local factors for improving the policy targeting. Indicators of spatial association and a spatial econometrics model were performed for the analysis. The results show regional agglomeration effects of the rate of participants to the measures adopted to promote organic farming. In addition, a spatial relation among the farms that obtain public support is found, highlighting that the diffusion of participation is driven mainly by imitation process and external economies of scale.

In this paper, I study the effect that switching to a voucher system of educational finance has on the distribution of income. The model is calibrated to U.S. data, and simulated for two different forms of education finance: a voucher system and a completely private system of schools. All voucher policies considered result in welfare gains and reductions in income inequality. A private system entails a welfare loss and an increase in income inequality. The more important the peer group is to future income, the smaller the welfare gains and reductions in inequality associated with voucher systems, and the greater the welfare cost and increase in inequality associated with a private system.