Fig. 1.

Timeline of the experiment. After self-administration of either placebo or oxytocin participants waited for at least 30 min before receiving instructions for the rule-task. In the rule task, each ball has to be dragged into either the blue or the yellow bucket. The rule is to put each ball into the blue bucket, which only yields €0.05 per ball, whereas putting a ball into the yellow bucket yields €0.10.