Unconscious determinants of free decisions in the human brain. Nat Neurosci

Ghent Institute for Functional and Metabolic Imaging of the brain, Ghent University, Gand, Flanders, Belgium
Nature Neuroscience (Impact Factor: 16.1). 06/2008; 11(5):543-5. DOI: 10.1038/nn.2112
Source: PubMed


There has been a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. We found that the outcome of a decision can be encoded in brain activity of prefrontal and parietal cortex up to 10 s before it enters awareness. This delay presumably reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness.


Available from: Chun Siong Soon
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    • "Because this readiness potential must detach from the rest of cognition, it is no longer integrated. For example, following up on Libet's original experiments, Soon et al. (2008) demonstrated that, by monitoring activity in the frontopolar prefrontal cortex, they could predict a participant's decision to move their right or left hand several seconds before the participant became aware of it. However, assuming people's behaviour is irreversibly integrated, then somewhere between the stimulus entering the brain and a decision to act leaving the brain, there must be a point where the information cannot be fully disentangled from the rest of cognition. "
    [Show abstract] [Hide abstract] ABSTRACT: In this article we explore the idea that consciousness is a language-complete phenomenon, that is, one which is as difficult to formalise as the foundations of language itself. We posit that the reason consciousness resists scientific description is because the language of science is too weak; its power to render phenomena objective is exhausted by the sophistication of the brain’s architecture. However, this does not mean that there is nothing to say about consciousness. We propose that the phenomenon can be expressed in terms of data compression, a well-defined concept from theoretical computer science which acknowledges and formalises the limits of objective representation. Data compression focuses on the intersection between the uncomputable and the finite. It has a number of fundamental theoretical applications, giving rise, for example, to a universal definition of intelligence (Hutter, 2004), a universal theory of prior probability, as well as a universal theory of inductive inference (Solomonoff, 1964). Here we explore the merits of considering consciousness in such terms, showing how the data compression approach can provide new perspectives on intelligent behaviour, the combination problem, and the hard problem of subjective experience. In particular, we use the tools of algorithmic information theory to prove that integrated experience cannot be achieved by a computable process.
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    • "The neural preparatory processes for action run from activity in higher cognitive areas to lower cognitive areas. dMPFC dorsomedial prefrontal cortex, RCZ rostral cingulate zone, SMA supplementary motor area, RP readiness potential, ERD eventrelated desynchronization Soon et al. 2008 ). The current study suggests that the process of intending develops during the process of acting, leaving traces in consciousness at certain points along the road, ultimately reaching awareness and becoming reportable . "
    [Show abstract] [Hide abstract] ABSTRACT: An intention to act has different onsets when it is measured in different ways. When participants provide a self-initiated report on the onset of their awareness of intending to act, the report occurs around 150 ms prior to action. However, when the same participants are repeatedly asked about their awareness of intending at different points in time, the onset of intending is found up to 2 s prior to action. This 'probed' awareness has its onset around the same time as the brain starts preparing the act, as measured using EEG. First of all, this undermines straightforward interpretations about the temporal relation between unconscious brain states and conscious intentions and actions. Secondly, we suggest that these results present a problem for the view that intentions are mental states occurring at a single point in time. Instead, we suggest the results to support the interpretation of an intention to act as a multistage process developing over time. This process of intending seems to develop during the process of acting, leaving reportable traces in consciousness at certain points along the road.
    No preview · Article · Feb 2016 · Experimental Brain Research
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    • "It has also been observed in more complex tasks, such as viewing the Rubin's vase-face picture, where not just whether a stimulus is perceived but how it is perceived is determined by the prestimulus activity state (Hesselmann et al., 2008a). Finally, intrinsic activity fluctuations have also been linked to behaviour in a free-decision button press task (Soon et al., 2008 ). In this, intrinsic activity was found to predict what response the participant was going to make before they were aware of making the decision as to which button to press and pressing it. "
    [Show abstract] [Hide abstract] ABSTRACT: Background: Spontaneous activity levels prior to stimulus presentation can determine how that stimulus will be perceived. It has also been proposed that such spontaneous activity, particularly in the default-mode network (DMN), is involved in self-related processing. We therefore hypothesised that pre-stimulus activity levels in the DMN predict whether a stimulus is judged as self-related or not. Method: Participants were presented in the MRI scanner with a white noise stimulus that they were instructed contained their name or another. They then had to respond with which name they thought they heard. Regions where there was an activity level difference between self and other response trials two seconds prior to the stimulus being presented were identified. Results: Pre-stimulus activity levels were higher in the right temporoparietal junction (RTPJ), the right temporal pole (RTP), and the left superior temporal gyrus in trials where the participant responded that they heard their own name than trials where they responded that they heard another. Conclusion: Pre-stimulus spontaneous activity levels in particular brain regions, largely overlapping with the DMN, predict the subsequent judgement of stimuli as self-related. This extends our current knowledge of self-related processing and its apparent relationship with intrinsic brain activity in what can be termed a rest-self overlap.
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