Institute of Psychology, Leiden University, Leiden, The Netherlands.
Center for Experimental Economics and Political Decision Making, University of Amsterdam, Amsterdam, The Netherlands.
Sci Rep. 2018 Jan 29;8(1):1827. doi: 10.1038/s41598-018-19997-5.
Decisions are often governed by rules on adequate social behaviour. Recent research suggests that the right lateral prefrontal cortex (rLPFC) is involved in the implementation of internal fairness rules (norms), by controlling the impulse to act selfishly. A drawback of these studies is that the assumed norms and impulses have to be deduced from behaviour and that norm-following and pro-sociality are indistinguishable. Here, we directly confronted participants with a rule that demanded to make advantageous or disadvantageous monetary allocations for themselves or another person. To disentangle its functional role in rule-following and pro-sociality, we divergently manipulated the rLPFC by applying cathodal or anodal transcranial direct current stimulation (tDCS). Cathodal tDCS increased participants' rule-following, even of rules that demanded to lose money or hurt another person financially. In contrast, anodal tDCS led participants to specifically violate more often those rules that were at odds with what participants chose freely. Brain stimulation over the rLPFC thus did not simply increase or decrease selfishness. Instead, by disentangling rule-following and pro-sociality, our results point to a broader role of the rLPFC in integrating the costs and benefits of rules in order to align decisions with internal goals, ultimately enabling to flexibly adapt social behaviour.
决策通常受到适当社会行为规则的制约。最近的研究表明，右侧前额叶皮层（rLPFC）通过控制自私行为的冲动，参与实施内部公平规则（规范）。这些研究的一个缺点是，必须从行为中推断出假设的规范和冲动，并且规范遵循和亲社会行为是不可区分的。在这里，我们直接让参与者面对一个要求自己或他人进行有利或不利的货币分配的规则。为了解决 rLPFC 在遵循规则和亲社会行为中的功能作用，我们通过应用阴极或阳极经颅直流电刺激（tDCS）来对其进行分歧性操作。阴极 tDCS 增加了参与者的规则遵循，即使是那些要求赔钱或在经济上伤害他人的规则。相比之下，阳极 tDCS 导致参与者更频繁地违反那些与参与者自由选择相悖的规则。因此，rLPFC 的脑刺激并没有简单地增加或减少自私。相反，通过将规则遵循和亲社会行为分开，我们的结果表明 rLPFC 在整合规则的成本和收益方面发挥着更广泛的作用，以便将决策与内部目标保持一致，最终能够灵活地适应社会行为。
