There Is No Free Won’t: Antecedent Brain Activity Predicts Decisions to Inhibit

PLOS ONE, Dec 2019

Inhibition of prepotent action is an important aspect of self-control, particularly in social contexts. Action inhibition and its neural bases have been extensively studied. However, the neural precursors of free decisions to inhibit have hardly been studied. We asked participants to freely choose to either make a rapid key press in response to a visual cue, or to transiently inhibit action, and briefly delay responding. The task required a behavioural response on each trial, so trials involving inhibition could be distinguished from those without inhibition as those showing slower reaction times. We used this criterion to classify free-choice trials as either rapid or inhibited/delayed. For 13 participants, we measured the mean amplitude of the ERP activity at electrode Cz in three subsequent 50 ms time windows prior to the onset of the signal that either instructed to respond or inhibit, or gave participants a free choice. In two of these 50 ms time windows (−150 to −100, and −100 to −50 ms relative to action onset), the amplitude of prestimulus ERP differed between trials where participants ”freely” chose whether to inhibit or to respond rapidly. Larger prestimulus ERP amplitudes were associated with trials in which participants decided to act rapidly as compared to trials in which they decided to delay their responses. Last-moment decisions to inhibit or delay may depend on unconscious preparatory neural activity.

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There Is No Free Won’t: Antecedent Brain Activity Predicts Decisions to Inhibit

Citation: Filevich E, Ku hn S, Haggard P ( There Is No Free Won't: Antecedent Brain Activity Predicts Decisions to Inhibit Elisa Filevich 0 Simone Ku hn 0 Patrick Haggard 0 Gilles Pourtois, University of Gent, Belgium 0 1 Institute of Cognitive Neuroscience, University College London , London , United Kingdom , 2 Department of Experimental Psychology and Ghent Institute for Functional and Metabolic Imaging, Ghent University , Gent , Belgium , 3 Centre for Lifespan Psychology, Max Planck Institute for Human Development , Berlin , Germany Inhibition of prepotent action is an important aspect of self-control, particularly in social contexts. Action inhibition and its neural bases have been extensively studied. However, the neural precursors of free decisions to inhibit have hardly been studied. We asked participants to freely choose to either make a rapid key press in response to a visual cue, or to transiently inhibit action, and briefly delay responding. The task required a behavioural response on each trial, so trials involving inhibition could be distinguished from those without inhibition as those showing slower reaction times. We used this criterion to classify free-choice trials as either rapid or inhibited/delayed. For 13 participants, we measured the mean amplitude of the ERP activity at electrode Cz in three subsequent 50 ms time windows prior to the onset of the signal that either instructed to respond or inhibit, or gave participants a free choice. In two of these 50 ms time windows (2150 to 2100, and 2100 to 250 ms relative to action onset), the amplitude of prestimulus ERP differed between trials where participants ''freely'' chose whether to inhibit or to respond rapidly. Larger prestimulus ERP amplitudes were associated with trials in which participants decided to act rapidly as compared to trials in which they decided to delay their responses. Lastmoment decisions to inhibit or delay may depend on unconscious preparatory neural activity. - Funding: This work was supported by the Wellcome Trust (http://www.wellcome.ac.uk/), an Overseas Research Students award from the British Council (http:// www.britishcouncil.org/new/) [EF], a Postdoctoral Fellowship from the Research Foundation Flanders (http://www.fwo.be/) [SK], an European Science FoundationEuropean Collaborative Research Project/Economic and social Research Council grant (RES-062-23-2183, http://www.esf.org/), and by a Leverhulme Trust Major Research Fellowship (http://www.leverhulme.ac.uk/) [PH]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Decisions for action can be decomposed into at least three separate functional components [1], associated with the selection of what action to make (what component); when to make it (when component) and whether to make it at all. The whether component is related to last-minute inhibition of an action that has been prepared and is ready for execution. This component may be particularly important as a mechanism for self-control [2]. These different forms of decision (what, when, whether) may be linked to different underlying neural processes. Previous studies have linked preparatory activity preceding voluntary action to decisions about what action to make e.g., [3 5], or when to make it [6,7]. Both these components of voluntary decision were shown to have unconscious neural precursors. First, decisions about when to act can bee associated with the readiness potential (RP), an accepted marker of neural preparation for action [6,8]. Libet [9] famously identified RPs already occurring around 200 ms prior to the conscious decision to move (when component). Second, Soon et al, [10] found that brain activity several seconds before conscious decision could predict which hand people chose to act with (what component). However, the decision about whether to act has received less attention. Such whether decisions can be taken at almost any stage during motor preparation, up until a point of no return [11]. Libet controversially suggested that last-minute decisions to inhibit action involved a purely conscious form of free wont. But theoretical grounds suggest that conscious decisions to inhibit must depend on unconscious brain processes, just like decisions to act [12]. However, neural precursors of voluntary inhibition have not yet been identified experimentally. We report an experiment in which participants had to either make a rapid key press action, or transiently inhibit executing the key press, so as to briefly delay their response. In this way we operationalized inhibition as a transient process, characterised by delayed responding, rather than as a complete suppression of all behavioural output. Our operational definition has the advantage of matching the action and inhibition conditions more closely, since both conditions include a m (...truncated)


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Elisa Filevich, Simone Kühn, Patrick Haggard. There Is No Free Won’t: Antecedent Brain Activity Predicts Decisions to Inhibit, PLOS ONE, 2013, Volume 8, Issue 2, DOI: 10.1371/journal.pone.0053053