Fig. 1.

Overview over the six experimental conditions and the two blocks. Each participant completed two blocks of six trials of the task. The two blocks differed by the magnitude of the initial endowments, which were increased by CHF 10 in Block 2 (high endowment block) relative to Block 1 (low endowment block). Within each block, the two recipients were either given equal endowments (Conditions 1, 4, 7, 10) or unequal endowments (Conditions 2, 3, 5, 6, 8, 9, 11, 12) in expectation; in the latter case, this resulted in a relatively poorer and a relatively richer potential recipient. In addition, initial endowments were either known with certainty (Conditions 1–3, 7–10), or with some degree of uncertainty (Conditions 4–6, 10–12). Under uncertainty, initial endowments were randomly and uniformly distributed in an interval of ± CHF 7.50 around the endowments in the Certain conditions. All members of each group (i.e. both recipients and the allocator) knew about the relative endowments of the two potential recipients in each group. The figure shows the information given to the participants about the endowments of Recipients A and B in each experimental condition. For each condition the top bar indicates the endowment of Recipient A, while the bottom bar indicates the endowment of Recipient B. In conditions 1–3 and 7–9 the exact endowments are indicated by black vertical lines inthe interior of the bar. In conditions 4–6 and 10–12 the startand endpoints of the endowment intervals are indicated by black vertical lines and the interval itself is filled with a darker grey shade