Brain preparation before a voluntary action: Evidence against unconscious movement initiation. Consciousness and Cognition, 19, 447-56

Dunedin School of Medicine, University of Otago, New Zealand
Consciousness and Cognition (Impact Factor: 2.31). 03/2010; 19(1):447-456. DOI: 10.1016/j.concog.2009.08.006


Benjamin Libet has argued that electrophysiological signs of cortical movement preparation are present before people report having made a conscious decision to move, and that these signs constitute evidence that voluntary movements are initiated unconsciously. This controversial conclusion depends critically on the assumption that the electrophysiological signs recorded by Libet, Gleason, Wright, and Pearl (1983) are associated only with preparation for movement. We tested that assumption by comparing the electrophysiological signs before a decision to move with signs present before a decision not to move. There was no evidence of stronger electrophysiological signs before a decision to move than before a decision not to move, so these signs clearly are not specific to movement preparation. We conclude that Libet’s results do not provide evidence that voluntary movements are initiated unconsciously.

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    • "subjects ∼200 ms before the onset of the actual movement , and up to ∼2 s after the onset of movement - related brain potentials , such as the readiness potential ( Shibasaki and Hallett , 2006 ) . Although both the validity of the W - moment as a reliable measure of the timing of the intention and the interpretation of the readiness potential as reflecting motor preparation have been criticized ( Gomes , 1998 ; Trevena and Miller , 2010 ; Schurger et al . , 2012 ) , following studies have replicated the main finding ( Haggard and Eimer , 1999 ; Soon et al . "
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    ABSTRACT: The temporal relationship between our conscious intentions to act and the action itself has been widely investigated. Previous research consistently shows that the motor intention enters awareness a few hundred milliseconds before movement onset. As research in other domains has shown that most behavior is affected by the emotional state people are in, it is remarkable that the role of emotional states on intention awareness has never been investigated. Here we tested the hypothesis that positive and negative affects have opposite effects on the temporal relationship between the conscious intention to act and the action itself. A mood induction procedure that combined guided imagery and music listening was employed to induce positive, negative, or neutral affective states. After each mood induction session, participants were asked to execute voluntary self-paced movements and to report when they formed the intention to act. Exposure to pleasant material, as compared to exposure to unpleasant material, enhanced positive affect and dampened negative affect. Importantly, in the positive affect condition participants reported their intention to act earlier in time with respect to action onset, as compared to when they were in the negative or in the neutral affect conditions. Conversely the reported time of the intention to act when participants experienced negative affect did not differ significantly from the neutral condition. These findings suggest that the temporal relationship between the conscious intention to act and the action itself is malleable to changes in affective states and may indicate that positive affect enhances intentional awareness.
    Frontiers in Psychology 08/2015; 6(1307). DOI:10.3389/fpsyg.2015.01307 · 2.80 Impact Factor
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    • "We assumed that the brain activity specific for hypnosis would be reflected as an observable increase in the excitability of M1. No facilitatory effect on corticospinal excitability was found in the TS condition, despite the fact that conscious motor intention emerges as a result of neural computations carried out within a parietal-motor network (Desmurget and Sirigu, 2009; Trevena and Miller, 2010), and that motor imagery facilitates corticospinal excitability (Kasai et al., 1997; Facchini et al., 2002). One plausible explanation is that cognitive inhibitory action might be exerted on the motor system (for a review see Aron et al., 2004): the right inferior frontal cortex suppressed electrical activity not only in the basal ganglia (Burman and Bruce, 1997), but also in the motor cortex (Sasaki et al., 1989). "
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    ABSTRACT: Hypnosis often leads people to obey a suggestion of movement and to lose perceived voluntariness. This inexplicable phenomenon suggests that the state of the motor system may be altered by hypnosis; however, objective evidence for this is still lacking. Thus, we used transcranial magnetic stimulation of the primary motor cortex (M1) to investigate how hypnosis, and a concurrent suggestion that increased motivation for a force exertion task, influenced the state of the motor system. As a result, corticospinal excitability was enhanced, producing increased force exertion, only when the task-motivating suggestion was provided during hypnotic induction, showing that the hypnotic suggestion actually altered the state of M1 and the resultant behavior.
    Neuroscience Research 06/2014; DOI:10.1016/j.neures.2014.05.009 · 1.94 Impact Factor
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    • "Investigations of free will have recently garnered widespread popular and scientific attention. These studies, however, often focus on some variation of the Libet experiments (Filevich, Kühn, & Haggard, 2013; Haggard, 2011; Lau, Rogers, Haggard, & Passingham, 2004; Libet, Gleason, Wright, & Pearl, 1983; Schurger, Sitt, & Dehaene, 2012; Trevena & Miller, 2010) or on probing people's intuitions regarding whether free will and moral responsibility are compatible with determinism (e.g., Nahmias, Morris, Nadelhoffer, & Turner, 2005; Nichols & Knobe, 2007). Empirical investigations into people's conceptualization of free will itself are virtually non-existent. "
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    ABSTRACT: Free will is the ability to transform thoughts and desires into actions, and this ability to act freely is presumed to underlie people's practice of moral praise and blame as well society's practice of legal punishment. However, many scholars believe that people's concept of free will is hopelessly corrupted by metaphysical assumptions, such as a belief in the soul or a belief in magical causation. Because science contradicts such metaphysical assumptions, science may also invalidate the ordinary concept of free will and thereby unseat a key requisite for moral and legal responsibility. Such a concern, however, turns on the exact content of people's concept of free will. Here we discuss a program of research that seeks to clarify the folk concept of free will and its role in moral judgment. Our data show that people have, not a metaphysical, but a psychological concept of free will: they assume that "free actions" are based on choices that fulfill one's desires and are relatively free from internal and external constraints. Moreover, we argue that these components—choice, desires, and constraints—lie at the heart of people's moral judgments. Once these components are accounted for, the abstract concept of free will contributes very little to people's moral judgments. What does it mean to have free will? When asked, people widely believe that they have free will (Baumeister, Crescioni, & Alquist, 2010), and free will is commonly asserted as a critical underpinning for moral and legal responsibility (Greene & Cohen, 2004). But for such a seemingly widespread and important concept, there is remarkable confusion over its definition and use. Philosophers and theologians have debated the question of free will for millennia. Today, neuroscientists and psychologists have joined philosophers in trying to answer some nagging questions about free will: Is it an illusion (Wegner, 2002)? Is it incompatible with determinism (Nichols, 2011)? Can people be morally responsible without it (Greene & Cohen, 2004)? However, what is the "it" in each of these questions? The "it" is the folk concept of free will. It is this concept that is suspected to be an illusion, incompatible with determinism, and required for moral responsibility. Unfortunately, scholars know very little about what constitutes this ordinary concept of free will. We therefore need clarity both on the concept and the underlying phenomenon, and in doing so we must go beyond philosophers' and scientists' intuitions. We must empirically examine ordinary people's conceptualization of free will and their application of this concept in everyday life. Without taking seriously the actual folk concept of free will, any theory of free will is at "risk of having nothing more than a philosophical fiction as its subject matter" (Mele, 2001, p. 27). Science and philosophy might discover facts that suggest revisions to the folk concept of free will; but without knowing what the concept is we can hardly revise it. * This chapter was made possible through the support of a grant from the Big Questions in Free Will project, funded by the John Templeton Foundation. The opinions expressed here are our own and do not necessarily reflect the views of the John Templeton Foundation.
    Surrounding Free Will, Edited by Alfred Mele, 01/2014: chapter Free will without metaphysics; Oxford University Press.
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