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Forschungsprojekte Prof. Dr. Vanessa Mertins

On the potential of promoting healthy behavior with small repeated commitment betting

Ido Erev, Gal Lifshitz, Yefim Roth, Maximilian Hiller, Stefan Klößner, Vanessa Mertins

Living a healthy lifestyle is a desirably yet mostly under achieved goal. Previous interventions using monetary incentives to promote desired healthy behavior led to mixed results: they were often expensive yet not always helpful. Building on the planning – ongoing gap, in the current paper we explore a novel procedure to promote desired behavior – repeated commitment betting: each day the participants can bet their own money on whether they are going to achieve their health goal on the next day. In case of success, the participants earns some small amount but in case of failure loose a larger amount. In the planning stage, when the betting decision Is made, most participants take the bet, because they plan to behave in accordance with their long term goals. In the ongoing stage, the prospect of loosing money helps participants behave in accordance with their long term interests. In two intervention studies (stress reduction breathing exercise and walking individually tailored number of steps), we validate the theoretical notian above, showing a major advantage of the betting procedure in achieving one’s goals compared to desired behavior incentivization and to control (fixed pay). Furthermore, the cost of the betting intervention was much smaller both per participant and per practice.     

commitment device, betting, healthy behavior, micro-incentives, deposit contracts, goal setting, monetary reward

The motivational effect of detailed job references for volunteers – Evidence from a field experiment on intergenerational cooperation

Ido Erev, Devin Kwasniok, Bernd Josef Leisen, Vanessa Mertins

The high importance of career-oriented motivations within the group of young volunteers and recent evidence that volunteering can improve employment opportunities, suggest that job references can motivate young adults to take up a social engagement, but not necessarily to carry it out regularly, with high intensity for a long period of time. We hypothesize that job references with information on individual engagement can motivate new volunteers to perform at a higher level compared to traditional references without individual performance information. In order to test this hypothesis, we implement both types of reference in a series of field experiments in which younger volunteers assist older citizens in completing tasks with their smartphone or tablet computer. The preliminarily results confirm that providing detailed performance information with the certificate increases the volume of individual volunteer work. The strength of this motivational effect varies depending on the underlying performance assessment mechanism (bonus system, single bet, repeated betting).

job references, virtual volunteering, nonmonetary incentives, habit formation, intergenerational cooperation, performance assessment mechanism

It wasn't me – unfair decision making and not standing up for it

Robert Gillenkirch, Torben Kölpin, Vanessa Mertins

Managers must regularly take unpleasant decisions which affect others.  In such situations, individuals are known to shift blame. We use two variants of the dictator game experiment: in the first setting, decision-makers choose the allocation and can lie about their responsibility for the resulting token distribution. In the second game, the allocation is decided by rolling a die while dictators can choose to misrepresent the result.  Our results confirm that dictators who favor themselves more also lie more often to conceal their responsibility. This effect is stronger for women than men, although women generally treat recipients more generously.

Lying, Responsibility, Decision-making, Dictator-game, Gender differences

Overcoming peer pressure to drink

Manuel Hoffmann, Bernd Josef Leisen, Vanessa Mertins

Excessive alcohol consumption imposes large costs to society. Already a one-time drinking episode can increase the probability of a variety of harmful events, ranging from serious physical injuries or traffic accidents to vandalism. Nevertheless, alcohol consumption is socially desirable in many situations and previous studies show that individuals even feel pressured to adapt their alcohol consumption to the perceived social drinking norm of their peers. In order to design effective interventions to overcome peer pressure to drink, a crucial first step is to align interventions to a general prevention approach. Should the intervention aim to correct misperceptions of one's own and group-related alcohol consumption, strengthen the individual to resist peer pressure or reduce peer pressure of the whole group? Motivated by a theoretical economic framework of social interactions, we conducted a series of field experiments with endogenously formed peer groups in night club settings (student party, discotheque and bar) to test the effectiveness of these three general prevention approaches. To the best of our knowledge, this is the first study aiming to mitigate peer pressure and influence perceived drinking norms while groups actively consume alcohol.

So far 414 subjects participated via 144 groups in our experiment in which each member of a peer group answered a short questionnaire, estimated their own and their peer group’s current alcohol level, performed a cognitive and a motor skill test and conducted a breath alcohol test on arrival and before leaving. Immediately after the first alcohol measurement we randomly assigned each group to one of four conditions to assess how their actual alcohol level and the accuracy of the alcohol level estimates change over time.

To demonstrate that individuals adapt their drinking behaviour to the average group alcohol level and thus feel peer pressure, we supplied some groups with feedback about their members alcohol level rank and their own rank while other groups randomly did not receive such a feedback. In line with our predictions, we find evidence that individuals with initially high alcohol levels within their groups reduce the growth of their alcohol levels. To examine whether it is effective to strengthen a group member to resist peer pressure or focus on reducing peer pressure at the group level, we introduce a bonus payment to a randomly selected peer that is below the average of its peers at the end. Either a single group member was selected immediately after the first alcohol measurement (ex-ante selection), or the entire group was informed that a random group member is selected after the last alcohol measurement (ex-post selection). We find suggestive evidence that ex-ante and ex-post selected individuals with high initial alcohol levels reduce their growth of alcohol level.

Preliminary results suggest that peer pressure to drink exist since individuals above (below) the average might feel pressured to reduce (increase) their consumption. Both ex-ante and ex-post incentives indicate a preventive effect on groups and individuals that arrive highly alcoholised.

Alcohol Prevention, Field Experiment, Peer Pressure, Drinking Norms, Live Feedback

Gift-exchange in society and the social integration of refugees: evidence from a field, a laboratory, and a survey experiment

Sabrina Jeworrek, Bernd Josef Leisen, Vanessa Mertins

In case of massive migration inflows, the integration of immigrants requires not only the provision of public services but also the contribution of the host country’s society. Given that only a limited number of individuals is willing to engage actively but most people are homines reciprocans, we examine the idea that the population’s willingness to support refugees increases as a reciprocal response to refugees’ contributions to society in the form of volunteer activities. By implementing a treatment intervention within a nationwide survey in Germany (N=1637) on the European migrant crisis beginning in 2015, we find that the willingness to support newcomers personally and financially indeed rises significantly. Importantly, this result also holds for a subgroup which is vital for the overall integration process: those who have not been in contact to refugees before. To observe not only a change in stated preferences but also in actual behavior, we conducted two additional experiments on a smaller scale ―which both confirm our findings.

Gift-exchange, reciprocity, refugees, integration

Working Paper