Khalighinejad Nima, Haggard Patrick
Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom.
Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom
Proc Natl Acad Sci U S A. 2016 Aug 2;113(31):8867-72. doi: 10.1073/pnas.1521223113. Epub 2016 Jul 19.
"Sense of agency" refers to the experience that links one's voluntary actions to their external outcomes. It remains unclear whether this ubiquitous experience is hardwired, arising from specific signals within the brain's motor systems, or rather depends on associative learning, through repeated cooccurrence of voluntary movements and their outcomes. To distinguish these two models, we asked participants to trigger a tone by a voluntary keypress action. The voluntary action was always associated with an involuntary movement of the other hand. We then tested whether the combination of the involuntary movement and tone alone might now suffice to produce a sense of agency, even when the voluntary action was omitted. Sense of agency was measured using an implicit marker based on time perception, namely a shift in the perceived time of the outcome toward the action that caused it. Across two experiments, repeatedly pairing an involuntary movement with a voluntary action induced key temporal features of agency, with the outcome now perceived as shifted toward the involuntary movement. This shift required involuntary movements to have been previously associated with voluntary actions. We show that some key aspects of agency may be transferred from voluntary actions to involuntary movements. An internal volitional signal is required for the primary acquisition of agency but, with repeated association, the involuntary movement in itself comes to produce some key temporal features of agency over the subsequent outcome. This finding may explain how humans can develop an enduring sense of agency in nonnatural cases, like brain-machine interfaces.
“能动感”指的是将一个人的自主行动与其外部结果联系起来的体验。目前尚不清楚这种普遍存在的体验是与生俱来的，源于大脑运动系统内的特定信号，还是相反，取决于联想学习，即通过自主运动与其结果的反复同时出现。为了区分这两种模式，我们要求参与者通过自主按键动作触发一个音调。自主动作总是与另一只手的非自主运动相关联。然后我们测试，即使省略了自主动作，非自主运动和音调的组合现在是否足以产生能动感。使用基于时间感知的隐性标记来测量能动感，即结果的感知时间向导致该结果的动作的偏移。在两个实验中，将非自主运动与自主动作反复配对，诱发了能动感的关键时间特征，现在结果被感知为向非自主运动偏移。这种偏移要求非自主运动之前与自主动作相关联。我们表明，能动感的一些关键方面可能从自主动作转移到非自主运动。能动感的初次获得需要一个内部意志信号，但随着反复关联，非自主运动本身在随后的结果上开始产生能动感的一些关键时间特征。这一发现可能解释了人类如何在非自然情况下，如脑机接口中，形成持久的能动感。
