Altered dopamine transmission is thought to influence the formation of persecutory delusions. However, despite extensive evidence from clinical studies there is little experimental evidence on how modulating the dopamine system changes social attributions related to paranoia, and the salience of beliefs more generally. Twenty seven healthy male participants received 150mg L-DOPA, 3 mg haloperidol, or placebo in a double-blind, randomised, placebo-controlled study, over three within-subject sessions. Participants completed a multi-round Dictator Game modified to measure social attributions, and a measure of belief salience spanning themes of politics, religion, science, morality, and the paranormal. We preregistered predictions that altering dopamine function would affect (i) attributions of harmful intent and (ii) salience of paranormal beliefs. As predicted, haloperidol reduced attributions of harmful intent across all conditions compared to placebo. L-DOPA reduced attributions of harmful intent in fair conditions compared to placebo. Unexpectedly, haloperidol increased attributions of self-interest about opponents’ decisions. There was no change in belief salience within any theme. These results could not be explained by scepticism or subjective mood. Our findings demonstrate the selective involvement of dopamine in social inferences related to paranoia in healthy individuals.

改变的多巴胺传递被认为会影响被害妄想的形成。然而，尽管临床研究提供了大量证据，但很少有实验证据表明调节多巴胺系统如何改变与偏执狂相关的社会归因，以及更普遍的信念的显着性。在一项双盲、随机、安慰剂对照研究中，27 名健康男性参与者在三个受试者内接受了 150 毫克左旋多巴、3 毫克氟哌啶醇或安慰剂。参与者完成了经过修改以衡量社会归因的多轮独裁者游戏，以及跨越政治、宗教、科学、道德和超自然主题的信仰显着性衡量。我们预先登记了改变多巴胺功能会影响（i）有害意图的归因和（ii）超自然信仰的显着性的预测。正如预测的那样，与安慰剂相比，氟哌啶醇在所有情况下都减少了有害意图的归因。与安慰剂相比，L-DOPA 在公平条件下减少了有害意图的归因。出乎意料的是，氟哌啶醇增加了对对手决定的自利归因。任何主题中的信念显着性都没有变化。这些结果不能用怀疑或主观情绪来解释。我们的研究结果表明，多巴胺选择性地参与了与健康个体的偏执狂相关的社会推论。任何主题中的信念显着性都没有变化。这些结果不能用怀疑或主观情绪来解释。我们的研究结果表明，多巴胺选择性地参与了与健康个体的偏执狂相关的社会推论。任何主题中的信念显着性都没有变化。这些结果不能用怀疑或主观情绪来解释。我们的研究结果表明，多巴胺选择性地参与了与健康个体的偏执狂相关的社会推论。