Berlin School of Mind and Brain & Department of Psychology, Humboldt-Universität zu Berlin, Germany.
Berlin School of Mind and Brain & Department of Psychology, Humboldt-Universität zu Berlin, Germany; Department of Experimental Psychology, Ghent University, Belgium.
Conscious Cogn. 2024 Sep;124:103732. doi: 10.1016/j.concog.2024.103732. Epub 2024 Aug 15.
The question of whether free will exists or not has intrigued philosophers for centuries. About 40 years ago, cognitive neuroscientists such as Benjamin Libet have joined the discussion by demonstrating that an ERP component, the readiness potential (RP), precedes the reported time of decision to act by a few hundred milliseconds. Libet et al. (1983) argued that our brains unconsciously prepare the movement before we experience any conscious intention, which led some free will skeptics (e.g., Ebert & Wegner, 2011) to argue that free will does not exist. While Libet's interpretation of his findings initiated an intense philosophical debate, alternative interpretations have been put forward more recently (Bode et al., 2014; Brass et al., 2019; Schurger et al., 2012; 2021). Integration to bound models (ITB) of Libet-style experiments suggest that we accumulate information until an intention threshold is reached, which triggers our experience of intention and execution of voluntary behaviors. The RP, from this perspective reflects the decision process itself rather than the consequence of an unconscious decision. To determine if the ITB model better predicts behavioral patterns in Libet-style experiments, we added a whether-component to the classical Libet task (the Veto Libet task) and compared the behavioral measures in the Veto Libet task with the Classical Libet task. We hypothesized that the signal accumulation in the Veto Libet task would be less steep than in the Classical Libet task, resulting in longer wait times and earlier self-reported intentions to act (i.e., the W). The result in general supported our hypotheses. In addition, these behavioral differences between the Classical Libet task and the Veto Libet task established valuable behavioral correlates for future investigations into the vetoing phenomenon. Finally, this study was also the first application of the Libet task in an online setting, and the behavioral parameters were highly comparable to the previous offline studies, further supporting the possibility of using the online platform to study arbitrary decision-making.
自由意志是否存在的问题困扰了哲学家几个世纪。大约 40 年前，本杰明·利贝特（Benjamin Libet）等认知神经科学家通过证明事件相关电位成分（准备电位，RP）在报告的行动决定时间之前提前几百毫秒出现，加入了讨论。Libet 等人（1983 年）认为，在我们经历任何有意识的意图之前，我们的大脑会无意识地准备运动，这导致一些自由意志怀疑论者（例如，Ebert 和 Wegner，2011）认为自由意志不存在。虽然利贝特对他的发现的解释引发了激烈的哲学辩论，但最近提出了替代解释（Bode 等人，2014 年； Brass 等人，2019 年；Schurger 等人，2012 年；2021 年）。Libet 式实验的整合到有界模型（ITB）表明，我们积累信息，直到达到意图阈值，这触发了我们对意图的体验和自愿行为的执行。从这个角度来看，RP 反映了决策过程本身，而不是无意识决策的结果。为了确定 ITB 模型是否更好地预测 Libet 式实验中的行为模式，我们在经典 Libet 任务（否决 Libet 任务）中添加了一个是否组件，并比较了否决 Libet 任务中的行为测量与经典 Libet 任务中的行为测量。我们假设，否决 Libet 任务中的信号积累会比经典 Libet 任务中更平缓，导致等待时间更长，自我报告的行动意图更早（即 W）。结果总体上支持我们的假设。此外，经典 Libet 任务和否决 Libet 任务之间的这些行为差异为未来对否决现象的研究建立了有价值的行为相关性。最后，这项研究也是在线设置中首次应用 Libet 任务，行为参数与之前的离线研究高度可比，进一步支持使用在线平台研究任意决策的可能性。
