Noninvasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation or transcranial direct and alternating current stimulation, are advocated as measures to enable causal inference in cognitive neuroscience experiments. Transcending the limitations of purely correlative neuroimaging measures and experimental sensory stimulation, they allow to experimentally manipulate brain activity and study its consequences for perception, cognition, and eventually, behavior. Although this is true in principle, particular caution is advised when interpreting brain stimulation experiments in a causal manner. Research hypotheses are often oversimplified, disregarding the underlying (implicitly assumed) complex chain of causation, namely, that the stimulation technique has to generate an electric field in the brain tissue, which then evokes or modulates neuronal activity both locally in the target region and in connected remote sites of the network, which in consequence affects the cognitive function of interest and eventually results in a change of the behavioral measure. Importantly, every link in this causal chain of effects can be confounded by several factors that have to be experimentally eliminated or controlled to attribute the observed results to their assumed cause. This is complicated by the fact that many of the mediating and confounding variables are not directly observable and dose–response relationships are often nonlinear. We will walk the reader through the chain of causation for a generic cognitive neuroscience NIBS study, discuss possible confounds, and advise appropriate control conditions. If crucial assumptions are explicitly tested (where possible) and confounds are experimentally well controlled, NIBS can indeed reveal cause–effect relationships in cognitive neuroscience studies.

无创脑刺激 (NIBS) 技术，如经颅磁刺激或经颅直流和交流电刺激，被提倡作为在认知神经科学实验中进行因果推断的措施。超越了纯粹相关神经影像测量和实验性感官刺激的局限性，它们允许以实验方式操纵大脑活动并研究其对感知、认知以及最终行为的影响。虽然这在原则上是正确的，但在以因果方式解释脑刺激实验时建议特别谨慎。研究假设通常过于简单化，忽略了潜在的（隐含假设的）复杂因果链，即刺激技术必须在脑组织中产生电场，然后在目标区域局部和网络的连接远程站点中唤起或调节神经元活动，从而影响感兴趣的认知功能并最终导致行为测量的变化。重要的是，这个因果效应链中的每一个环节都可能被几个因素混淆，这些因素必须通过实验消除或控制才能将观察到的结果归因于它们假设的原因。由于许多中介变量和混杂变量无法直接观察并且剂量-反应关系通常是非线性的，这一事实使情况变得复杂。我们将引导读者了解一般认知神经科学 NIBS 研究的因果链，讨论可能的混淆，并建议适当的控制条件。