Experimental Design Details
Before this main part of the experiment begins, subjects completed the Bomb Risk Elicitation Task (BRET), proposed by Crosetto and Filippin (2012) to measure risk attitudes.
In both treatments, the experiment is divided into two parts. Each part is preceded by the corresponding instructions, which are read aloud by the experimenters, and a comprehension test, highlighting the main concepts of each part.
In both parts of the experiment, subjects made antisocial choices. Subjects are randomly divided into groups of three subjects, that remain the same during the experiment. Subjects’ decisions can only affect the earnings of the members of their group. In each group, a subject has an initial income of 5€, a subject has an initial income of 7€, and a subject has an initial income of 10.50€. Initial incomes in a group are given randomly. During the experiment, subjects do not know their initial income. They see a table that shows their own and group members’ initial income. According to this table, they choose whether to attack another group member’s income or not. When they attack another group member, they choose the sum to be subtracted from the victim’s income in a range between 20 cents and 100 cents. Attacking costs 1/5 of the sum that has been subtracted from the victim. To maintain initial incomes unknown, subjects are shown three scenarios, that differ in the allocations of initial incomes. Every time subjects are asked to make an attack choice, they make a choice for each scenario. In each set of choices, only a choice is made correspondingly to the real initial income and can be used to determine earnings at the end of the experiment. As subjects do not know their real initial income, each choice has the same probability to be used.
As above-mentioned, the experiment is divided into two parts. In the first part, subjects make choices with no future mobility, whilst in the second part, subjects make choices with future mobility. In the second part, choices are made twice: not knowing the real transition matrix that will be applied to their initial income (i.e., with the value “p” unknown), and knowing it.
In both treatments, choices in the second part are preceded by the effort test, which is the slider task, proposed by Gill and Prowse (2012). In the “Effort treatment”, subjects give expectations about the test results before completing the slider task, knowing the test that is used and how it works, and after, to collect information about ex-ante and ex-post self-confidence. They are asked to give their expected number of correct answers and the percentage of participants they expect to have a lower score than their own. In the “Random treatment”, subjects give their expectations about the lottery results one time. They are asked to give the interval in which they expect their number to lie and the percentage of participants they expect to have received a lower drawn number than their own.
At the end of the experiment, subjects have decided on three sets of attack choices, each of which is composed of three attack choices (i.e., one for each possible initial income in each set). A set of antisocial decisions is randomly drawn. If the drawn set is the first one, the decision chosen in the first set considering the real initial income is applied to the initial income (given that in the first part mobility is not considered). If the drawn set is the second (third) one, the decision chosen in the second (third) set considering the real initial income is applied to the initial income (given that in the first part mobility is not considered).