Fig 1.
Difference between downstream and upstream reciprocity.
This figure illustrates the difference between downstream and upstream reciprocity. In both cases, A is the person who cooperates with B, and C is the person B cooperates with. The arrow filled in orange is the one who cooperates first, and the dashed arrows are those who cooperate later. Downstream reciprocity is a mechanism whereby if you cooperate with someone, someone else who has been observing you will cooperate with you. On the one hand, upstream reciprocity means that if someone cooperates with me, I will also cooperate with someone else.
Fig 2.
An overview of the experiment and all participants are Role B in the figure. The color of the arrows in the previous figure differs from that in the figure above because the actions in the chain are different. The arrows in the previous figure represent cooperation, whereas the arrows in this figure represent take, so the colors of the arrows have been changed.
Fig 3.
Violin plot of the amount of cooperation to third parties in each treatment.
The vertical axis of this figure was truncated at 0 and 100 to exclude the data outside this range.
Table 1.
Effect of the belief in a just world on negative upstream reciprocity.
Fig 4.
Comparison of positive and negative upstream reciprocity.
In the figure, “Chain strength” compares the strength of the chain of positive and negative upstream reciprocal cooperation for each condition. The words and arrows in the same row have different colors for positive and negative because they have different behaviors. The orange arrow represents give, and the blue arrow represents take. The meanings of words are reversed in positive and negative because the actions are relative. For example, “Full” for positive upstream reciprocity means full give, and “Full” for negative upstream reciprocity means full take.